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   35831篇
  免费   2365篇
  国内免费   139篇
医药卫生   38335篇
  2022年   337篇
  2021年   684篇
  2020年   426篇
  2019年   624篇
  2018年   769篇
  2017年   561篇
  2016年   744篇
  2015年   821篇
  2014年   992篇
  2013年   1214篇
  2012年   2043篇
  2011年   2058篇
  2010年   1149篇
  2009年   1031篇
  2008年   1737篇
  2007年   1806篇
  2006年   1773篇
  2005年   1693篇
  2004年   1474篇
  2003年   1405篇
  2002年   1283篇
  2001年   967篇
  2000年   868篇
  1999年   862篇
  1998年   380篇
  1997年   331篇
  1996年   270篇
  1995年   257篇
  1994年   224篇
  1993年   216篇
  1992年   487篇
  1991年   478篇
  1990年   502篇
  1989年   473篇
  1988年   430篇
  1987年   472篇
  1986年   423篇
  1985年   435篇
  1984年   341篇
  1983年   260篇
  1982年   202篇
  1979年   326篇
  1978年   252篇
  1977年   214篇
  1975年   202篇
  1974年   223篇
  1973年   219篇
  1972年   249篇
  1971年   226篇
  1969年   196篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
BACKGROUND: Radioiodine therapy (RIT) combined with glucocorticoids is an effective therapy for Graves' disease, but it is debatable whether glucocorticoids should be applied in patients without Graves' ophthalmopathy (GO). METHODS: The effect of 0.4 - 0.5 mg prednisone every second day over a period of 5 weeks after RIT was monitored over a follow-up period of at least 12 months after RIT. A questionnaire was sent to 186 consecutive patients without GO concerning eye symptoms after RIT. 148 patients (80 %) answered. If eye symptoms had occurred after RIT, additional clinical examination was carried out at our outpatient clinic. The primary endpoint was the absence or onset of GO within the first year after RIT. RESULTS: Within 12 months after RIT the examination confirmed GO in 5 out of 148 patients (3.4 %). In all cases the symptoms were transient. No adverse reaction to the use of prednisone after RIT was noted. CONCLUSIONS: The risk of new GO in the first year after RIT was low and the clinical course of GO was mild when RIT was combined with a low-dose glucocorticoid regimen. Preventive administration of glucocorticoids can therefore be recommended in patients with Graves' disease even without evident GO.  相似文献   
3.
The aim of the current study was to investigate whether alterations in N-terminal pro brain natriuretic peptide (NT-proBNP) reflect changes in right ventricular structure and function in pulmonary hypertension patients during treatment. The study consisted of 30 pulmonary hypertension patients; 15 newly diagnosed and 15 on long-term treatment. NT-proBNP, right heart catheterisation and cardiac magnetic resonance imaging measurements were performed, at baseline and follow-up. There were no significant differences between newly diagnosed patients and those on treatment at baseline or follow-up with respect to NT-proBNP, haemodynamics and right ventricular parameters. Relative changes in NT-proBNP during treatment were correlated to the relative changes in right ventricular end-diastolic volume index (r = 0.59), right ventricular mass index (r = 0.62) and right ventricular ejection fraction (r = -0.81). N-terminal pro brain natriuretic peptide measurements reflect changes in magnetic resonance imaging-measured right ventricular structure and function in pulmonary hypertension patients. An increase in N-terminal pro brain natriuretic peptide over time reflects right ventricular dilatation concomitant to hypertrophy and deterioration of systolic function.  相似文献   
4.
PURPOSETo study the relationship of lumbar facet joint tropism to degeneration of the cartilage and subcortical bone in the facet joints and the effect of tropism in intervertebral disk degeneration.METHODSThe orientation of 104 cadaveric lumbar facet joints with respect to sagittal plane was measured on CT scans, and the joints were classified as having no tropism, mild tropism, or severe tropism. On MR images, the severity of cartilage degeneration and bony sclerosis was measured. The correlation between tropism and degeneration was calculated, as was the relationship among age, spinal level, and degeneration.RESULTSWe identified four spinal levels with severe tropism, six with moderate tropism, and 94 without tropism. Cartilage degeneration was not significantly more severe in the joints with tropism than in the joints without. Sclerosis was slightly greater in the joints with tropism than in the joints without it. Sclerosis and cartilage degeneration were significantly related to age and spinal level.CONCLUSIONAge, spinal level, and overall facet joint angle are more important factors in facet joint degeneration than is tropism.  相似文献   
5.
Most of the nearly 1,000 fatal bicycle-related injuries annually could be prevented if riders used safety helmets. Helmet use by adult bicyclists has received relatively little attention because educational campaigns to promote helmet use generally focus on children. Helmet use by adult and child bicyclists at 120 suburban and rural sites in three Maryland counties was observed on two Saturdays in 1990-91 during an evaluation of the impact of a mandatory helmet law. Concordance or discordance of helmet use within various groups of bicyclists--adults only, adults with children, and children only--was recorded. Helmet use among 2,068 adult bicyclists was 49 percent, 51 percent, and 74 percent in the three counties. In two counties combined, 52 percent (365 of 706) of solo adult bicyclists wore helmets compared with only 5 percent (5 of 94) of solo child bicyclists (P < .001). Helmet use or nonuse was concordant among 87 percent of 277 adult-adult pairs, 94 percent of 50 child-child pairs, and 91 percent of 32 adult-child pairs of bicyclists observed. Concordance rates of helmet use or nonuse were similarly high among pairs of adult bicyclists of the same or mixed sexes. These data are consistent with the concept that both adults and children tend to adopt the helmet-wearing behaviors of their companions. Public health efforts focused on adults should encourage helmet use by adult bicyclists both to prevent head injuries and to provide a role model for children.  相似文献   
6.
7.
The aim of the current research project was to explore the possibilities of combining pressurized carbon dioxide with hot stage extrusion during manufacturing of solid dispersions of itraconazole and polyvinylpyrrolidone-co-vinyl acetate 64 (PVP-VA 64) and to evaluate the ability of the pressurized gas to act as a temporary plasticizer as well as to produce a foamed extrudate. Pressurized carbon dioxide was injected into a Leistritz Micro 18 intermeshing co-rotating twin-screw melt extruder using an ISCO 260D syringe pump. The physicochemical characteristics of the extrudates with and without injection of carbon dioxide were evaluated with reference to the morphology of the solid dispersion and dissolution behaviour and particle properties. Carbon dioxide acted as plasticizer for itraconazole/PVP-VA 64, reducing the processing temperature during the hot stage extrusion process. Amorphous dispersions were obtained and the solid dispersion was not influenced by the carbon dioxide. Release of itraconazole from the solid dispersion could be controlled as a function of processing temperature and pressure. The macroscopic morphology changed to a foam-like structure due to expansion of the carbon dioxide at the extrusion die. This resulted in increased specific surface area, porosity, hygroscopicity and improved milling efficiency.  相似文献   
8.
In 50 children, 4 months to 12 years of age, with minor head trauma non-target visual event-related potentials were performed and compared to a second registration of the potentials some months later. On following-up there was a clear tendency for a relative improvement of the latencies of the endogenous potentials. In this way non-target visual event-related potentials proved to be of value in the investigation of mental impairment in early childhood.  相似文献   
9.
Postoperative prophylaxis with antiinflammatory medications, primarily indomethacin, is extremely effective in preventing the severest degrees of heterotopic ossification (HO) after a total hip arthroplasty (THA) and the recurrence of excised HO developed after a previous hip surgery. Prophylaxis with indomethacin should be given in 25-mg doses three times daily for at least three weeks, starting on the first postoperative morning. However, a shorter treatment period may be equally effective in preventing the severest degrees of HO, and a postoperative delay of five days before the initiation of prophylaxis does not seem to be followed by the development of severe HO. As evaluated one year after surgery, treatment with antiinflammatory medications in the immediate postoperative weeks did not increase the incidence of implant-bone interface radiolucencies, aseptic loosening, or revisions in cemented or cementless THAs when compared with cases that did not have postoperative treatment. However, although no major complications have been reported regarding the use of antiinflammatory medications in the prevention of HO after THA, orthopedic surgeons prescribing such treatment should be aware of their contraindications as well as early and late side effects. Since several antiinflammatory agents are reported to be effective in preventing HO, future reports dealing with HO after THA should always include information about the postoperative antiinflammatory treatment used.  相似文献   
10.
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