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   13372篇
  免费   569篇
  国内免费   89篇
医药卫生   14030篇
  2024年   8篇
  2023年   128篇
  2022年   258篇
  2021年   455篇
  2020年   241篇
  2019年   314篇
  2018年   404篇
  2017年   284篇
  2016年   436篇
  2015年   498篇
  2014年   632篇
  2013年   706篇
  2012年   906篇
  2011年   906篇
  2010年   535篇
  2009年   475篇
  2008年   896篇
  2007年   1022篇
  2006年   982篇
  2005年   908篇
  2004年   795篇
  2003年   636篇
  2002年   566篇
  2001年   153篇
  2000年   130篇
  1999年   118篇
  1998年   77篇
  1997年   49篇
  1996年   59篇
  1995年   35篇
  1994年   24篇
  1993年   23篇
  1992年   33篇
  1991年   27篇
  1990年   27篇
  1989年   34篇
  1988年   27篇
  1987年   24篇
  1986年   20篇
  1985年   22篇
  1984年   10篇
  1983年   13篇
  1982年   8篇
  1981年   8篇
  1979年   11篇
  1978年   10篇
  1973年   10篇
  1972年   11篇
  1971年   9篇
  1966年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Thirteen CD4+ T-cell clones raised against Mycobacterium leprae from three M. leprae-vaccinated subjects were studied for major histocompatibility complex (MHC) restriction in proliferative and cytotoxicity assays. These T-cell clones recognized at least nine different epitopes, ranging from M. leprae-specific to broadly crossreactive. Restriction studies with a panel of antigen-presenting cells (APCs) suggest that all of the T-cell clones recognized antigens in the context of the DR locus. Three T-cell clones with three different reactivities from a DR1, 2-positive subject responded to M. leprae in proliferation and cytotoxicity when the antigen was presented in the context of DR1-positive APCs. Four T-cell clones responding to M. leprae-specific or crossreactive epitopes from the second donor, who was DR4,DW4; DR4,Dw14-positive, and a single M. leprae-specific T-cell clone from the third subject, who was DR3,4:Dw4, recognized the antigens in the presence of Dw4 APCs. Four crossreactive T-cell clones from the second subject responded in the presence of Dw14-positive APCs, and one limited crossreactive clone recognized the antigen in the context of DR4 and DR7-positive cells, suggesting that its response was restricted by a common determinant. The T-cell clones that recognize the 65-kDa, 18-kDa, and 13B3 recombinant M. leprae antigens in proliferative assays were cytotoxic for autologous adherent cells pulsed with the respective antigens.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
23.
This case report presents a very rare and long-standing causeof infertility, osseous metaplasia of the endometrium, and describesits successful management by hysteroscopy. A woman with a historyof induced abortion 12 years ago, failed to conceive from thattime on. The infertility work-up was unrevealing except forthe presence of intracavitary calcification on ultrasonography.After diagnostic hysteroscopy, solid bony spicules coveringthe posterior wall of the endometrial cavity were removed bywire loop resectoscope. Histology established the diagnosisof osseous metaplasia of the endometrium. The patient conceivedin her second spontaneous cycle and has an ongoing pregnancyat the time of writing. Hysteroscopy was an effective meansof extracting this heterotopic tissue, thereby re-establishingfertility even after a long period of infertility.  相似文献   
24.
25.
We report on a Turkish family in which the father and his two sons were diagnosed as having the KBG syndrome. Large upper central incisors were the diagnostic finding in all three patients along with mental retardation, cryptorchidism, skeletal abnormalities, and short stature. Our report clearly confirms that the inheritance is autosomal dominant in KBG syndrome, although a high male to female ratio has been observed in published cases.  相似文献   
26.
Objective: To evaluate the use of serodiagnosis for tuberculosis and leprosy using mycobacterial antigen 38 kDa, with kits from Omega laboratories, to detect IgG by enzyme immunoassay (EIA).
Method: The study population consisted of 58 patients with evidence of tuberculous infection (culture of Mycobacterium tuberculosis complex or microscopic evidence), of whom 23 had pulmonary and 35 had extrapulmonary disease. There were six subjects who had recently been treated for tuberculosis, 11 patients on treatment for leprosy and 137 patients suspected of having tuberculosis on clinical or radiologic grounds (without laboratory evidence). A control group comprised 35 healthy individuals or patients suffering from diseases other than tuberculosis.
Results: The tests showed that there was a significant difference in antibody levels between the patients with active pulmonary disease, extrapulmonary tuberculosis and leprosy in comparison with the control group ( p <0.001). The sensitivities of the two tests together for proven pulmonary tuberculosis were 100% and 95.7% at 1.0–1.5 and >1.6 EIA cut-off points respectively, while the specificities were 88.5% and 100% at the same cut-off points. The sensitivities for extrapulmonary tuberculosis were 71.4% and only 51.4% at 1.0–1.5 and >1.6 EIA cut-off points. The test was positive in 30 (21.9%) of the 137 suspected patients, while 43 (31.4%) had an equivocal result and the remaining 64 (47.7%) suspects were definitely negative. There was again a significant difference in positivity rates between suspects and the control group.
Conclusions: Omega IgG test is useful in the serodiagnosis of active pulmonary tuberculosis and leprosy, but less sensitive in extrapulmonary disease, particularly in children. Equivocal results may only add to the evidence of tuberculosis in early or minimal disease.  相似文献   
27.
Histological examination of the metastatic rat mammary adenocarcinoma line MTLn3 showed that macrophages and mast cells were frequently localized at the tumor periphery in the stromal tissues adjacent to the zones of tumor invasion. The interactions of these host cells with tumor cells and tumor-associated fibroblasts could be important in stimulating the production of extracellular matrix-degrading enzymes that facilitate tumor invasion and metastatic spread. Therefore, we examined the effects of isolated, activated macrophages and mast cells on the secretion of collagenolytic activities by normal fibroblasts, metastatic mammary adenocarcinoma cells and tumor-associated fibroblasts. Medium from activated macrophages or degranulated mast cells stimulated significant increases in production of collagenolytic activities by normal and tumor-associated fibroblasts and MTLn3 tumor cells. Medium from activated macrophages that had been pretreated with medium from degranulated mast cells, however, were less stimulatory to fibroblasts and tumor cell production of collagenolytic activities than medium from degranulated mast cells alone. We also examined the effects of two cytokines, interleukin-1 and tumor necrosis factor-a on activated macrophage- and degranulated mast cell-stimulation of fibroblast and tumor cell collagenolytic activities. The two cytokines alone or in combination stimulated increased production of collagenolytic activities by fibroblasts and tumor cells. Addition of the cytokines to degranulated mast cell products resulted in secretion of higher collagenolytic enzyme activities by normal fibroblasts (but not by tumor-derived fibroblasts or tumor cells) than with degranulated mast cell product-treatment of either target cell alone. Cytokines used in combination with macrophage-conditioned medium were less effective in stimulating fibroblast and tumor cell collagenase activities than cytokines alone. Thus normal infiltrating host cells such as macrophages and mast cells can have profound effects on the production of degradative enzymes by tumor cells and tumor-associated stromal fibroblasts.  相似文献   
28.
BACKGROUND: Aeroallergen sampling provides information regarding the onset, duration and severity of the pollen season that clinicians use to guide allergen selection for skin testing and treatment. OBJECTIVES: This atmospheric survey reports (1) airborne pollen contributions in Adana in one-year period (2) pollen onset, duration and peak level (3) the relationship between airborne pollen and selected meteorological variables and; (4) effects on symptoms in pollen allergic children. METHODS: Pollen sampling was performed with a volumetric Burkard Spore Trap. Meteorological data were measured daily from April 2001 to April 2002. Asthma symptom scores were investigated in 186 pollen allergic children that were on follow up in pediatric allergy outpatient clinics during same period. RESULTS: Average measurements included 82.5% tree pollen, 7.7% grass pollen and 9.8% herb pollen 54 taxa were identified during one year. The most prominent tree pollens were Cupressaceae, Eucalyptus and Pinus. The most common herb was Chenopodiaceae pollen family. When airborne pollen levels were examined in relation to single meteorological conditions; daily variations in total pollen counts were not significantly correlated with any variable studied (humidity, rainfall, temperature and wind) (p > 0.05). On the other hand, statistically significant relationship between pollen concentration and symptom scores were found (p > 0.05). Positive correlations were seen between both Gramineae and Herb pollen, and humidity and rainfall from March to July. However, positive correlations were detected between tree pollen counts and temperature and humidity in May and June. CONCLUSION: This survey is the first volumetric airborne pollen analysis conducted in the survey area in Adana. This study suggested that the effects of weather on pollen count and symptom scores in this population could not be clearly identified with the evaluation of one-year data. However, pollen counts had effect on allergic symptoms in pollen allergic children. Examination of the complex interaction of multiple whether parameters would perhaps more fully elucidate the relationship between meteorology and aerobiology and provide the clinician with information necessary to forecast pollen prevalence. An awareness of the ever chancing, local aeroallergen patterns requires regular monitoring. Such awareness serves as a useful guide in the effective testing and treatment of atopic patients.  相似文献   
29.
INTRODUCTION: One of the most common and important side effects of 5-fluorouracil (5-FU) is mucositis with ulcerations in the oral cavity. We investigated the effects of local cryotherapy on mucositis incidence administrated durng 5-FU treatment. METHODS: In a total of 99 courses, 5-FU and folinic acid combination chemotherapy was given to 40 patients. In our study, we considered every course as a single case, and cryotherapy was given to the same patient in one course but not given in the next. RESULTS: While mucositis developed in 6.7% of the courses given with cryotherapy, this ratio was 38.9% in courses given without cryotherapy. In the logistic regression analysis, development of mucositis had been found to correlate only with cryotherapy. Odds ratio (OR) = 11.5; in the 95% confidence interval (CI) = 3.2 - 41.9; (p = 0.001). DISCUSSION: Results of initial studies evaluating the effects of cryotherapy in preventing mucositis due to 5-FU based chemotherapy regimens were promising. We concluded that oral cooling prevents 5-FU induced mucositis. This effective prophylactic treatment should be used in patients who are at increased risk for developing 5-FU induced mucositis.  相似文献   
30.
Systemic administration of isoprenaline to rats produced a dose-dependent increase in water drinking which was effectively blocked by propranolol. This dipsogenic effect was significantly inhibited by the subacute (4 days) administration of imipramine (18.1. mg/kg/day) together with either the H1-histamine receptor antagonist, chlorpheniramine (0.1 or 1.32 mg/kg/day), or the H2-histamine antagonist, cimetidine (1.91 mg/kg/day) or ranitidine (0.60 or 1.51 mg/kg/day). The oral subacute administration of imipramine alone had no significant effect on this behavior. However, chronic ingestion of imipramine alone (21 days) caused a significant reduction in the isoprenaline-induced behavior.It is concluded that the desensitization of central beta-adrenoceptors, as evidenced by inhibition of isoprenaline-induced drinking, can be accelerated following the oral subacute co-administration of imipramine with either H1- or H2-histamine receptor antagonists. It also seems that central histamine receptors may partially contribute towards the mechanism of antidepressant effect of imipramine.  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