首页 | 本学科首页   官方微博 | 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   25177篇
  免费   2360篇
  国内免费   77篇
耳鼻咽喉   260篇
儿科学   593篇
妇产科学   344篇
基础医学   3068篇
口腔科学   804篇
临床医学   3269篇
内科学   5398篇
皮肤病学   614篇
神经病学   1857篇
特种医学   1029篇
外科学   3540篇
综合类   469篇
一般理论   24篇
预防医学   2670篇
眼科学   352篇
药学   2008篇
中国医学   23篇
肿瘤学   1292篇
  2021年   359篇
  2020年   206篇
  2019年   346篇
  2018年   377篇
  2017年   278篇
  2016年   333篇
  2015年   384篇
  2014年   528篇
  2013年   833篇
  2012年   1133篇
  2011年   1118篇
  2010年   633篇
  2009年   581篇
  2008年   1034篇
  2007年   1042篇
  2006年   1085篇
  2005年   1098篇
  2004年   1022篇
  2003年   982篇
  2002年   970篇
  2001年   978篇
  2000年   1008篇
  1999年   855篇
  1998年   326篇
  1997年   270篇
  1996年   256篇
  1995年   266篇
  1994年   216篇
  1993年   218篇
  1992年   612篇
  1991年   630篇
  1990年   589篇
  1989年   523篇
  1988年   489篇
  1987年   485篇
  1986年   482篇
  1985年   475篇
  1984年   343篇
  1983年   297篇
  1982年   220篇
  1981年   209篇
  1979年   327篇
  1978年   238篇
  1977年   204篇
  1975年   166篇
  1974年   214篇
  1973年   204篇
  1972年   169篇
  1971年   192篇
  1970年   170篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A new autosomal recessive mutation, characterized by an early defect in righting reflex and stiffened gait, progression to severe spasticity, tremor and rigidity, and death before weaning, appeared spontaneously on the C57BL/6 background. It was shown to be an allele of the mutant spastic spa, and shall be known as spaAlb. Mutant levels of [3H]strychnine binding are less than 10% of control levels in the brainstem and spinal cord. Autoradiographic examination of the distribution of [3H]strychnine binding sites in the mutant confirm a greatly reduced level of binding compared to control in all areas of the spinal cord, brainstem, and midbrain.  相似文献   
72.
73.
The first case report of systemic evenomation by the five-ringed brown snake, Pseudonaja modesta, is presented. The patient had mild general symptoms of envenomation only, with no coagulopathy or evidence of paralysis. Data on P. modesta venom is presented, which shows an absence of a coagulant component in this venom. The venom gives a positive reaction to brown snake venom in the CSL Venom Detection Kit.  相似文献   
74.
75.
Nonadherence is common in the U.S. dialysis population. No single strategy has been definitely proven to yield universal and/or lasting improvements in adherence. However, using a patient-centered approach, including the removal of barriers to adherence, ongoing education, and cognitive behavioral strategies, may generate increased opportunities for patients and the nephrology staff to improve both adherence and outcomes.  相似文献   
76.
77.
78.
SETTING: A tuberculosis (TB) prevalence survey was performed in 2002 in two urban communities in Cape Town, South Africa. The population was 36,334 in 2001, and the TB notification rate was 341 per 100,000 population for new smear-positive TB in 2002. OBJECTIVE: To evaluate the relative contributions of symptom and chest radiographic (CXR) screening in the detection of subjects with smear- and/or culture-positive TB in prevalence surveys. DESIGN: Information on symptoms, CXR abnormalities, sputum smear and culture was gathered from a random cluster sample of 1170 adults (aged > or = 15 years). Smear and/or culture-positive TB was used as the gold standard. RESULTS: Of 1170 adults, 29 had bacteriologically positive TB (smear- and/or culture-positive). The presence of any abnormalities on CXR had the highest sensitivity for detecting subjects with bacteriologically positive TB (0.97, 95%CI 0.90-1.00). Specificity for any abnormalities on CXR was 0.67 (95%CI 0.64-0.70). The specificity of any of five TB-related symptoms was 0.68 (95%CI 0.65-0.71). Individual symptoms had low sensitivities, ranging from 0.10 for fever to 0.54 for cough of > or = 2 weeks. CONCLUSION: In this TB prevalence survey, CXR screening, but not symptom screening, was a sensitive alternative to sputum examination of all participants.  相似文献   
79.
The mechanism of platelet thrombus growth on an artificial surface is incompletely understood. While glycoprotein (GP)Ib and GPIIb/IIIa are required for normal attachment and thrombus formation on subendothelium, their roles in platelet deposition to artificial surfaces remain unclear. Using selected platelet inhibitors (aspirin [ASA], low molecular weight dextran, monoclonal antibodies 10E5 [v GPIIb/IIIa], and 6D1 [GPIb]) we examined the mechanism of platelet deposition to polyethylene (PE) surfaces under steady laminar and oscillatory flow conditions. Polyethylene-100 (PE-100) tubes (0.86 mm internal diameter) were perfused under steady laminar flow with citrated human whole blood reconstituted with 111indium-labeled platelets at 312 seconds-1 shear rate in the presence and absence of platelet inhibitors. The effect of oscillatory flow on platelet deposition was examined in a microwell system using 3/16-inch diameter discs of National Heart, Lung, and Blood Institute primary reference PE as the test surface. ASA and dextran did not significantly (P greater than .05) inhibit platelet deposition in laminar flow (not tested in oscillatory). Antibody 10E5 was a potent inhibitor (laminar less than 1%, P less than .0001, oscillatory less than 1.6%, P less than .01) of platelet deposition in both systems, and in this case, true adhesion (first attached layer) was blocked. Antibody 6D1 unexpectedly inhibited 70% of platelet deposition (P less than .01) in steady laminar flow and 56.5% in oscillatory flow (P less than .01). Scanning electron microscopy demonstrated platelets atop platelets in the controls, rare platelets in the 10E5 group, and a patchy monolayer of platelets in the 6D1 group. Transmission electron microscopy of cross-sections confirmed these observations. We conclude that the adhesion of the first platelet layer to an artificial surface requires GPIIb/IIIa. The data also suggest that GPIb is required for the development of the second layer in vertical platelet thrombus growth.  相似文献   
80.
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