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   1077950篇
  免费   71934篇
  国内免费   1375篇
耳鼻咽喉   15032篇
儿科学   34728篇
妇产科学   28676篇
基础医学   153767篇
口腔科学   29581篇
临床医学   95143篇
内科学   204408篇
皮肤病学   24473篇
神经病学   81632篇
特种医学   43019篇
外国民族医学   201篇
外科学   163470篇
综合类   21879篇
现状与发展   1篇
一般理论   265篇
预防医学   74796篇
眼科学   24652篇
药学   86375篇
  7篇
中国医学   2819篇
肿瘤学   66335篇
  2019年   7835篇
  2018年   11390篇
  2017年   8973篇
  2016年   10180篇
  2015年   11361篇
  2014年   15409篇
  2013年   22334篇
  2012年   30763篇
  2011年   32539篇
  2010年   19091篇
  2009年   17921篇
  2008年   30079篇
  2007年   32204篇
  2006年   32842篇
  2005年   31189篇
  2004年   29879篇
  2003年   28644篇
  2002年   27600篇
  2001年   60079篇
  2000年   61529篇
  1999年   50980篇
  1998年   12456篇
  1997年   11025篇
  1996年   11025篇
  1995年   10335篇
  1994年   9351篇
  1993年   8867篇
  1992年   37821篇
  1991年   36302篇
  1990年   35762篇
  1989年   34308篇
  1988年   30877篇
  1987年   30004篇
  1986年   28237篇
  1985年   26468篇
  1984年   19208篇
  1983年   16126篇
  1982年   8844篇
  1979年   17049篇
  1978年   11427篇
  1977年   10247篇
  1976年   8851篇
  1975年   10082篇
  1974年   11665篇
  1973年   11287篇
  1972年   10764篇
  1971年   10111篇
  1970年   9271篇
  1969年   8952篇
  1968年   7925篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
PURPOSE: Concern over stigma as a consequence of genetic testing has grown in response to the recent increase in genetic research and testing resulting from the Human Genome Project. However, whether a genetic or hereditary basis necessarily confers a stigma to a condition remains unexamined. METHODS: We performed a qualitative interview study with 86 individuals with one of four conditions: deafness or hearing loss, breast cancer, sickle cell disease, and cystic fibrosis. The first two groups were divided approximately between people who ascribed their conditions to a genetic or hereditary cause and those who did not. RESULTS: Respondents interpreted genetic or hereditary causes and nongenetic causes in a variety of ways. Subjects with breast cancer reported the most consistently negative interpretation of genetic cause. This response concerned future ill health, not an enduring sense of stigma. Deaf and hard of hearing subjects provided the most consistently positive comments about a genetic or hereditary basis to their condition, casting familial hearing loss as a vital component of group and individual identity. Respondents with sickle cell disease and cystic fibrosis offered similar and positive interpretations of the genetic cause of their condition insofar as it meant their conditions were not contagious. CONCLUSIONS: Although some subjects report feeling stigmatized as a result of their condition, this stigmatization is not uniformly associated with the condition's cause, genetic or otherwise. Instead, stigma emerges from a variety of sources in the context of the lived experience of a particular condition.  相似文献   
103.
Despite significant improvements in the prognosis of acute promyelocytic leukemia brought about by therapeutic advances, understanding of the epidemiology of acute promyelocytic leukemia remains limited. Earlier reports have suggested that Hispanics may have an increased incidence of acute promyelocytic leukemia, but no systematic analysis of national data has yet been reported. We performed a retrospective cohort study, using data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute from 1992-2001 in order to compare leukemia incidence rates as a function of race and ethnicity. We identified 709 cases of acute promyelocytic leukemia and analyzed incidence rates by race and sex. Hispanics were not found to have greater lifetime incidence rates than whites, with an incidence relative rate (IRR) of 0.86 that of whites (P=0.17). The age distribution among Hispanics was significantly different from non-Hispanic whites, with greater incidence rates for children ages 1-19 years (IRR=1.9, P=0.02) and adult ages 20-44 years (IRR=1.6, P=0.004). Blacks had lower lifetime incidence rates than non-Hispanic whites (IRR=0.75, P=0.04), Hispanics (IRR=0.64, P=0.007), and Asians (IRR=0.67, P=0.03). Asians did not differ from non-Hispanic whites in lifetime or age-specific incidence rates. These results indicate that while US Hispanics do not have greater lifetime incidence rates of acute promyelocytic leukemia, blacks have lower incidence rates of acute promyelocytic leukemia than Hispanics, non-Hispanic whites, and Asians.  相似文献   
104.
The authors studied the cumulative probability of pregnancy for up to 4 consecutive embryo transfer (ET) cycles with ICSI performed for male factor. Transfers could be either fresh or frozen. The clinical pregnancy rate (PR) for the first 4 cycles were similar [44% (61/366); 31% (44/138); 45% (14/31); 44% (4/9)]. Delivery rates were also similar. There was a lower PR on the second retrieval vs. the first retrieval (47% vs. 29%), but this may be related to most of the second retrievals occurring in the second transfer cycle (67%, 31/55); this may be explained by women who were poor responders and required another retrieval without a frozen ET. The majority of transfers in cycle 1 were fresh, whereas cycles 2-4 used primarily frozen-thawed embryos. These data should be helpful for patients requiring IVF with ICSI in deciding to continue with more IVF cycles or consider other  相似文献   
105.
The frequency and pathophysiology of freezing of gait (FoG) in atypical parkinsonism is unknown. We analysed the frequency of FoG in postmortem-confirmed atypical parkinsonian disorders (APD) comprising corticobasal degeneration (CBD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP). Sixty-six patients with pathologically confirmed APD (CBD, n = 13; DLB, n = 14; MSA, n = 15; PSP, n = 24) formed the basis for a multicenter clinicopathological study. Clinical features at first and last clinical visit were abstracted from patient records on standardized forms following strict instructions. At the first visit (median 36 months after symptom onset), 24% of APD had FoG (CBD, 8%; DLB, 21%; PSP, 25%; MSA, 40%). Logistic regression analysis showed a significant association of FoG and urinary incontinence (P = 0.04) at first visit. At last visit, 47% of APD had FoG (CBD, 25%; PSP, 53%; DLB, 54%; MSA, 54%). Clinicopathological correlation based on routine postmortem examination failed to identify a consistent neuropathological substrate of FoG. This study demonstrates that (1) FoG is common in APD, and (2) urinary incontinence is significantly associated with FoG in these disorders. Whether FoG and urinary incontinence share similar neuropathological substrates remains to be determined by future studies.  相似文献   
106.
Summary Experimental data suggest that multidrug resistance in cancer may be overcome by using an increased dose of anticancer agent(s) in combination with a resistance-modifying agent (RMA). We studied the pharmacokinetics and metabolism of both epirubicin (EPI) and verapamil (VPL) to explore the possible pharmacokinetic interactions between these two drugs. Ten patients with advanced breast cancer were given EPI (40 mg/m2 in a daily i.v. bolus for 3 consecutive days), and five of them also received VPL (4×120 mg/daily p.o. for 4 consecutive days). The data indicated a significant interaction between these two drugs that affected their metabolism. The areas under the concentration-time curves (AUC) obtained for epirubicin glucuronide, epirubicinol glucuronide, and both of the 7-deoxy-aglycones were higher in the EPI+VPL group as compared with the EPI group. The AUC, terminal half-life, mean residence time, volume of distribution at steady state, and plasma clearance of EPI alone as compared with EPI+VPL did not differ significantly. These results suggest either an induction of enzymes necessary for drug metabolism or an increase in the liver blood flow, resulting in an enhanced generation of metabolites with time or in an inhibition of excretion processes. Comparisons of the AUC values obtained for EPI and its metabolites after the first, second, and third injections of EPI revealed a cumulative effect for the metabolites that was more pronounced in the EPI+VPL group, being significant (P<0.05) for epirubicin glucuronide in both treatment groups and for epirubicinol glucuronide in the EPI+VPL group. Maximal concentrations of VPL and nor-VPL reached 705±473 and 308±122 ng/ml, respectively, with the steady-state concentrations being 265±42 ng/ml for VPL and 180±12 ng/ml for nor-VPL.This study was supported by the Erich und Gertrud Roggenbuck-Stiftung zur Förderung der Krebsforschung (Hamburg). The anthracycline metabolites were kindly provided by Dr. A. Suarato (Farmitalia, Milano, Italy); nor verapamil was provided by Dr. Traugott (Knoll, Ludwigshafen, Germany)  相似文献   
107.
108.
109.
The role of hypertension and antihypertensive drugs in cardiovascular complications was evaluated in 380 elderly people living in the Tokyo Metropolitan Gerontology Center. The subjects were classified into four groups according to the presence or absence of hypertension and their antihypertensive treatment, and followed up prospectively for 5 years from 1979 to 1984. The average age of each group was 74 to 76 years. Cerebrovascular disease was observed in 19.3% of male hypertensives and 10.1% of male normotensives (p = 0.078). The drug treated group revealed no cerebral hemorrhage and less cerebral infarction. This tendency was not observed in females. Ischemic heart disease was prevalent in the drug treated group (10.9% vs 4.5%, p = 0.023) irrespective of blood pressure level. Risk factors such as body mass index, skinfold thickness, serum cholesterol, albumin, creatinine, blood urea nitrogen and uric acid at entry were elevated in the drug treated group. Diuretics were used in 92% of the drug treated group; in 53% as monotherapy and in 39% as combination therapy with other antihypertensive agents. The metabolic effect of diuretics may increase the incidence of ischemic heart disease in the elderly. We might conclude that hypertension in the aged accelerates cerebrovascular complications, and that antihypertensive treatment is effective even in this group. However, the wide use of diuretics could increase the incidence of ischemic heart disease. Careful selection of antihypertensive drugs as well as dose adjustment are needed in the treatment of elderly hypertensives.  相似文献   
110.
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