首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8444篇
  免费   534篇
  国内免费   40篇
医药卫生   9018篇
  2023年   77篇
  2022年   132篇
  2021年   239篇
  2020年   150篇
  2019年   180篇
  2018年   249篇
  2017年   199篇
  2016年   255篇
  2015年   252篇
  2014年   341篇
  2013年   401篇
  2012年   594篇
  2011年   650篇
  2010年   355篇
  2009年   318篇
  2008年   556篇
  2007年   582篇
  2006年   469篇
  2005年   476篇
  2004年   496篇
  2003年   441篇
  2002年   446篇
  2001年   107篇
  2000年   101篇
  1999年   95篇
  1998年   96篇
  1997年   73篇
  1996年   69篇
  1995年   40篇
  1994年   42篇
  1993年   39篇
  1992年   55篇
  1991年   49篇
  1990年   45篇
  1989年   38篇
  1988年   35篇
  1987年   33篇
  1986年   37篇
  1985年   31篇
  1984年   34篇
  1983年   18篇
  1982年   16篇
  1981年   12篇
  1979年   14篇
  1978年   7篇
  1977年   7篇
  1976年   7篇
  1974年   10篇
  1973年   9篇
  1968年   7篇
排序方式: 共有9018条查询结果,搜索用时 0 毫秒
1.
2.
The expression of insulin-like growth factor binding proteins (IGFBPs) in the developing mouse submandibular and von Ebner’s glands was determined by in situ hybridization and by an immunohistochemical method. In the submandibular glands, IGFBP-2 and IGFBP-4 mRNAs were expressed in the terminal end-buds (TEB) at E13–E17, concomitant with epithelial branching. IGFBP-3 mRNA was expressed in the mesenchyme surrounding the TEB; and IGFBP-5 mRNA, in the ducts. At E17, IGFBP-5 mRNA expression was observed not only in the ducts but also in the TEB. Similarly, IGFBP-4 mRNA expression was observed not only in the TEB but also in the mesenchyme. After birth, IGFBP-4 expression was observed only in the connective tissue and disappeared by P14. That of IGFBP-7 appeared at P1 and was observed in the connective tissue until P21. The IGFBP-5 mRNA expression pattern after birth was the same as that seen at E17, but at P21 IGFBP-5 was immunohistochemically expressed only in the duct. The mRNA level of IGFBP-2 expression at postnatal days was weak, but its protein was detected in the ducts and acini at P14–P21. In von Ebner’s glands, which appeared at the base of the circumvallate papillae at E17, only IGFBP-2 and IGFBP-4 mRNAs were expressed in the ducts and acini. Postnatally, IGFBP-4 was substituted by IGFBP-5 in the same region. Immunohistochemically, IGFBP-5 and IGFBP-2 were expressed in the ducts and acini at P14–P21. Throughout the study, IGFBP-6 was not detected by in situ hybridization, the immunoreactivity for it was observed in the nerve fibers of submandibular and von Ebner’s glands. These data support a role for these molecules as local mediators of salivary growth and differentiation.  相似文献   
3.
Some physiological substances, including acetylcholine and nitric oxide, are useful candidates for stimulation of intestinal absorption of drugs. In the present study, we elucidated the ability of epinephrine (Epi) to stimulate the intestinal absorption of drugs. We evaluated the ability of Epi to enhance absorption of macromolecules using dextran (Mw 4000 Da), which is poorly absorbed from the intestine, as a model compound in situ in a closed loop of the rat jejunum. Treatment of the jejunum with Epi resulted in significant increase in absorption of dextran in a dose-dependent fashion. The area under the curve (AUC) from 0 to 4 h in the Epi-treated jejunum was 13-fold higher than that in the vehicle-treated jejunum. The absorption-enhancing activity of Epi was 40-fold higher than that of caprate, a clinically used absorption-enhancer of drugs. In the experimental conditions used in this study, histological injury of the mucosa and perturbation of the mucosal membrane were not observed in the Epi-treated jejunum. Treatment with an antagonist of alpha-adrenergic receptors attenuated the stimulation of intestinal absorption by Epi, and treatment with an agonist of alpha-adrenergic receptors resulted in enhancement of intestinal absorption. While an antagonist of beta-adrenergic receptors enhanced the absorption-enhancing effect of Epi, an agonist of beta-adrenergic receptors stimulated intestinal absorption. These results indicate that stimulation of adrenergic receptors may be a novel strategy for intestinal absorption of drugs.  相似文献   
4.
The pathomorphological and clinical findings were investigated in 10 cases of drug-induced hypersensitivity nephritis. Hypersensitivity due to drugs was strongly suggested by the lymphocyte stimulation test in all patients. The offending drugs included penicillin, cephem derivatives, nonsteroidal anti-inflammatory drugs, and minocycline. All patients developed acute renal failure shortly after administration of regular doses of the drugs. Allergic symptoms plus a raised level of serum IgE or eosinophilia were seen in 7 patients. The remaining 3 patients receiving nonsteroidal anti-inflammatory drugs had no allergic symptoms, but developed severe proteinuria. Eight patients without severe glomerular damage recovered after withdrawal of the offending drugs and temporal dialysis and/or steroid therapy. Renal biopsies revealed tubulitis and tubular epithelial degeneration with interstitial edema as the common characteristic findings. Granulomatous lesions were occasionally observed. Multinucleated giant cells found in the granulomas were positive for LN-3 which is compatible with HLA-DR antigen. The glomeruli appeared normal, except in 2 cases in whom crescentic glomerulonephritis and thrombotic microangiopathy were seen. Our study suggests that the lymphocyte stimulation test and renal biopsy are the most useful means to confirm the diagnosis and provides further evidence for the participation of cell-mediated immunity in the pathogenesis of drug-induced hypersensitivity nephritis.  相似文献   
5.
Abstract: Light microscopic observations on the superficial pineal gland of Wistar-King rats were made to examine whether or not pineal volume and pinealocyte size, expressed as nuclear density, at daytime or nighttime are affected by long-term exposure to 50 Hz rotating magnetic field (MF) at 5.0 μT. Determinations of pineal volume and pinealocyte size were repeated twice (April and October) during the year. Size of pinealocytes in MF-exposed and sham-exposed rats exhibited, in addition to the difference between peripheral and central regions, regional differences in a proximodistal direction; pinealocytes in the distal and middle-peripheral regions were usually larger than those in the proximal and middle-central regions at daytime or nighttime. In October, distal and proximal pinealocytes showed significant day-night changes in size in sham-exposed rats, but not in MF-exposed animals. The situations in the two groups were almost reversed in April. Significant day-night differences were scarcely found in pinealocyte size in the middle region in the two groups. Throughout the study, pineal volume and pinealocyte size in each region were generally the same between MF-exposed and sham-exposed rats at daytime or nighttime. The results suggest that pinealocytes in the distal and proximal regions, but not those in the middle region, are affected by MF-exposure; day-night differences in sizes of distal and proximal pinealocytes appear in April and disappear in October under the influence of MF. MF may exert an effect on mechanisms controlling day-night rhythms of pinealocyte size in the rat.  相似文献   
6.
A 10-year-old girl with autoimmune hepatitis (AIH) was reported. She was admitted to our hospital because of cholestasis and elevation of liver enzymes for 2 months. Laboratory examination revealed that EBV-DNA copy number in the PBMNC (peripheral mononuclear cells) was 1.2 x 10(3) copies/microg of DNA, hypergammaglobulinemia, and positive antinuclear antibody, positive anti-smooth muscle antibody. The histology of her liver biopsy specimen revealed interface hepatitis, dense mononuclear cell infiltrates, mild fibrosis, and negative for EBV in situ hybridization assay indicating AIH and not EBV-associated hepatitis. She was treated firstly with methylprednisolone pulses, then will prednisolone p.o.+azathioprine p.o.. Intravenous cyclophosphamide pulse therapy was introduced because of her abnormal immune pathology. All abnormal laboratory parameters improved to normal levels within 2 months, and EBV-DNA copy number in the PBMNC became negative after 4 months. The histology of liver biopsy specimen was useful for the diagnosis of AIH in such a difficult case needed to be differentiated from EBV hepatitis.  相似文献   
7.
Morning blood pressure is reported to be more closely related to hypertensive organ damages such as left ventricular mass index, microalbuminuria and silent cerebral infarcts, than blood pressure at other times of the day. Morning blood pressure may play an important role in the pathogenesis of hypertensive target organ damage. Increased sympathetic nerve activity is reported to be one of the mechanisms of morning hypertension; however, there are no available data that show whether strict home blood pressure control, especially in the morning period, can reduce target organ damage. The Japan Morning Surge-1 (JMS-1) study includes hypertensive outpatients with elevated morning systolic blood pressure (>or=135 mmHg) as assessed by self-measured blood pressure monitoring at home. All enrolled patients are under stable antihypertensive medication status. Exclusion criteria are arrhythmia, chronic inflammatory disease, and taking alpha-blockers or beta-blockers. The target number of patients to be enrolled in the JMS-1 study is 600, and the aim is to evaluate differences in the markers of hypertensive target organ damage, such as brain natriuretic peptide and the urinary albumin excretion/creatinine ratio. All of the patients are randomized to an experimental group or a control group, with randomization to be carried out by telephone interviews with the patients' physicians. In the experimental group, patients begin taking additional antihypertensive medication just before going to bed. This consists of doxazosin 1 mg/day, which then is increased to 2 mg/day and 4 mg/day, with a beta-blocker added after a 1-month interval until the morning systolic blood pressure is controlled to less than 135 mmHg. Patients in the control group continue the treatment they are receiving at the enrollment for 6 months. Blood pressure levels, adverse effects, and hypertensive target organ damage before and after the study are evaluated. In the JMS-1 study, we will evaluate whether strict morning blood pressure control by sympathetic nervous system blockade using an alpha-blocker, doxazosin, and with the addition of a beta-blocker if needed, can reduce hypertensive target organ damage.  相似文献   
8.
9.
Abstract: The effects of zinc on the production of active oxygen species were investigated in rat neutrophils by chemilumi-nescence and spectrophotometric assays. The luminol-dependent chemiluminescence in unstimulated neutrophils showed a single peak. Zinc at concentrations lower than 0.1 mM augmented the intensity of chemiluminescence and showed a bimodal pattern, the first peak of which was inhibited by superoxide dismutase and catalase, while the second peak disappeared in the presence of catalase, but was unaffected by superoxide dismutase. At the same concentrations of zinc, O2? and H2O2 production increased, but secretion and activity of myeloperoxidase were not affected. Zinc at 0.1 mM enhanced the second peak of luminol-dependent chemiluminescence, and concomitantly O2? and H2O2 production of neutrophils stimulated with formyl-methionyl-leucyl-phenylalanine. Homogenized neutrophils showed a bimodal pattern on induction by zinc, the second peak of which was inhibited slightly by catalase and completely by sodium azide, but was not inhibited by superoxide dismutase. Zinc-induced O2? production was inhibited by pertussis toxin, but was not significantly inhibited by a protein kinase C inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), or a calmodulin antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). These results suggest that zinc can augment luminol-dependent chemiluminescence by increasing O2? production through the classical signal transduction pathway, and by increasing H2O2 not via O2?.  相似文献   
10.
Pain-related somatosensory evoked potentials (pain SEPs) following CO2 laser stimulation were examined in 30 patients with peripheral neuropathies, and the results were compared with clinical sensory findings. Pain SEP findings showed a significant correlation with the clinical impairment of pain sensation, but not with the impairment of deep sensations. In contrast, conventional electrically-stimulated SEPs (electric SEPs) showed a significant correlation with deep sensations, but not with the impairment of pain sensation. Examinations of both pain SEPs and electric SEPs, therefore, are considered to be very useful to evaluate physiological functions of sensory nerves in patients with peripheral neuropathies.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号