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   6291篇
  免费   446篇
  国内免费   38篇
耳鼻咽喉   27篇
儿科学   175篇
妇产科学   125篇
基础医学   1263篇
口腔科学   146篇
临床医学   515篇
内科学   1363篇
皮肤病学   99篇
神经病学   509篇
特种医学   360篇
外国民族医学   1篇
外科学   773篇
综合类   56篇
一般理论   3篇
预防医学   294篇
眼科学   120篇
药学   473篇
中国医学   4篇
肿瘤学   469篇
  2021年   84篇
  2020年   57篇
  2019年   69篇
  2018年   85篇
  2017年   72篇
  2016年   76篇
  2015年   111篇
  2014年   141篇
  2013年   206篇
  2012年   254篇
  2011年   258篇
  2010年   173篇
  2009年   162篇
  2008年   234篇
  2007年   240篇
  2006年   251篇
  2005年   226篇
  2004年   191篇
  2003年   217篇
  2002年   211篇
  2001年   161篇
  2000年   190篇
  1999年   186篇
  1998年   104篇
  1997年   96篇
  1996年   87篇
  1995年   71篇
  1994年   82篇
  1993年   64篇
  1992年   124篇
  1991年   106篇
  1990年   136篇
  1989年   124篇
  1988年   113篇
  1987年   106篇
  1986年   121篇
  1985年   124篇
  1984年   64篇
  1983年   51篇
  1981年   58篇
  1979年   77篇
  1978年   59篇
  1977年   52篇
  1975年   68篇
  1973年   55篇
  1972年   54篇
  1971年   52篇
  1970年   54篇
  1969年   64篇
  1968年   52篇
排序方式: 共有6775条查询结果,搜索用时 31 毫秒
1.
2.
A high resolution depth attenuation product (Kdhires) was developed using MODIS 500 m and 250 m spectral bands. The Kdhires was compared with Wang’s operational Kd for the Chesapeake Bay. Minimal differences were observed between the two methods, with greatest deviation occurring in areas of high turbidity in the tributaries. After tuning the new Kdhires, the mean absolute error and bias between the two algorithms was 0.22 m?1 and 0.026 m?1, indicating good agreement. Higher spatial resolution provides for improved retrievals along the coast and into the narrow sections of the tributaries, coinciding with areas of concern to estuarine health and coastal management applications.  相似文献   
3.
4.
The case report presents a 25-year-old woman who got pregnant twice in 1 year. Both pregnancies were terminated after ultrasound examination demonstrated limb abnormalities. Radiological and pathological examinations showed diastrophic dysplasia, a rare form of an osteochondrodysplasia with autosomal recessive inheritance. Here the histopathological findings in the cartilage and prenatal diagnosis by ultrasound are discussed.  相似文献   
5.
6.
In NMRI mice superovulation with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) increased mating rate, number of implantation sites, rate of advanced and delayed resorptions, as well as retarded sternebral ossification and cleft palate. On day 3 of gestation in preimplantation embryos, cell number and mitotic index were lower after superovulation than after spontaneous ovulation. However, when preimplantation embryos from superovulated and control females were transferred on day 3 of pregnancy to pseudopregnant recipients (10 embryos per female) no differences could be detected between the two groups of fetuses at term. The results of the embryo transfer experiments indicate that abnormal embryonic development after superovulation with gonadotropins is predominantly induced by effects of the hormone treatment on the maternal uterine environment.  相似文献   
7.

Hintergrund:  

Die nosokomiale Pneumonie gehört zu den häufigsten nosokomialen Infektionen und ist die häufigste auf der Intensivstation. Die nosokomiale Pneumonie ist mit einer signifikanten Mortalität und Morbidität assoziiert, und ihr Auftreten verschlechtert die Prognose des Patienten deutlich. Nach der Definition der DRGs auch im deutschen Krankenhaussystem ist die nosokomiale Pneumonie überwiegend Sache des Krankenhauses und kann somit nicht nur das Ergebnis der Patientenbehandlung, sondern auch das finanzielle Ergebnis des Krankenhauses beeinträchtigen.  相似文献   
8.
For several genetic diseases two biological phenomena have been recognised as important: germline mosaicism; and different new mutation rates in males and females depending on mutation type. Both principles have been investigated separately and their influence on risk estimation in families has been exemplified in the literature. The aim of this paper is to present a general model that includes mosaicism and different new mutation rates. Mosaicism is introduced by defining additional alleles at the disease locus in combination with adapted segregation rules. Taking Duchenne muscular dystrophy as an example, we derive the conditions which have to be fulfilled for a population in mutation selection equilibrium. Our approach describes the model at the population level and not in individual subjects. This has the advantage of being able to use well known algorithms for the calculation of likelihoods in pedigrees, and to include additional diagnostic information such as marker genotypes and carrier deletion test results. We demonstrate the impact of the new model on a typical pedigree. In families where the patient is not available, the distinction between point mutations and deletions is important, since often molecular diagnostic tests for females can only screen for deletions. Negative deletion test results can now be included in the risk calculations.  相似文献   
9.
Lotus footdrop: sciatic neuropathy in the thigh   总被引:1,自引:0,他引:1  
C M Vogel  R Albin  J W Alberts 《Neurology》1991,41(4):605-606
  相似文献   
10.
A 37-year-old Italian male developed a myocardial infarct with subsequent ventricular fibrillation. He was defibrillated seven times with up to 360 Joules. Thirteen days later the patient died of recurrent myocardial infarct due to thrombotic occlusion of the left circumflex coronary artery. At autopsy, necrosis of the right pectoralis muscle was observed. Electroporation is the pathogenetic mechanism of skeletal muscle damage due to multiple defibrillations with high energy levels. Received: 8 January 1998 Accepted: 15 April 1998  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