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   20676篇
  免费   1166篇
  国内免费   175篇
耳鼻咽喉   366篇
儿科学   875篇
妇产科学   548篇
基础医学   2840篇
口腔科学   696篇
临床医学   2040篇
内科学   3785篇
皮肤病学   593篇
神经病学   1979篇
特种医学   1043篇
外国民族医学   4篇
外科学   2683篇
综合类   347篇
一般理论   17篇
预防医学   1548篇
眼科学   401篇
药学   1156篇
  5篇
中国医学   118篇
肿瘤学   973篇
  2023年   173篇
  2022年   254篇
  2021年   553篇
  2020年   396篇
  2019年   442篇
  2018年   622篇
  2017年   486篇
  2016年   565篇
  2015年   677篇
  2014年   813篇
  2013年   984篇
  2012年   1230篇
  2011年   1129篇
  2010年   756篇
  2009年   731篇
  2008年   918篇
  2007年   1043篇
  2006年   909篇
  2005年   928篇
  2004年   923篇
  2003年   838篇
  2002年   722篇
  2001年   470篇
  2000年   465篇
  1999年   441篇
  1998年   262篇
  1997年   234篇
  1996年   166篇
  1995年   145篇
  1994年   128篇
  1993年   134篇
  1992年   226篇
  1991年   203篇
  1990年   188篇
  1989年   168篇
  1988年   193篇
  1987年   157篇
  1986年   148篇
  1985年   142篇
  1984年   127篇
  1983年   101篇
  1982年   98篇
  1981年   86篇
  1980年   66篇
  1979年   108篇
  1978年   97篇
  1977年   66篇
  1975年   90篇
  1974年   83篇
  1973年   104篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
101.
Zusammenfassung Für die Todeszeitbestimmung kann der Speisebreiverteilung im Magendarmtrakt zentrale Bedeutung zukommen. Dabei würde die Zeitschätzung durch eine postmortale Magenentleerung zusätzlich erschwert. Auch anhand radiologischer Kontrolle unmittelbar postmortal in den Magen applizierten Röntgenkontrastbreies fand sich kein Anhalt für eine postmortale peristaltische Entleerung des Mageninhaltes im Tierexperiment.Herrn Prof. Dr. S. Berg in Verehrung zum 65. Geburtstag gewidmet  相似文献   
102.
103.
A cohort of 38-year-old men and women were studied for leisure time physical exercise in relation to low back pain (LBP), education, work, social class and smoking by a self-administered questionnaire. At the age of 14 years, the subjects had been interviewed by their school doctor regarding history of LBP and radiographs of the thoracic and lumbar spine were taken. The results show no positive correlation between radiographic changes and LBP in the adolescent period and decreased physical activity in adulthood. Physical activity for at least 3 h/week reduces the risk of LBP measured as lifetime, 1-year and point prevalence. Eighty-five percent of the subjects who reported taking physical exercise for at least 3 h/week had participated in sports activity almost constantly since their school days and these reported being in better condition than the rest of the cohort. Otherwise they did not have a healthier mode of life. No physical exercise during leisure time was associated with a short school education, un-skilled work, unemployment and sickness, low social class, divorce, living in an apartment and smoking. Sixty percent had never or not for many years been interested in participating in sports. Badminton and tennis were the most common sports practised (36%), followed by gymnastics (32%), ball games — soccer and team handball - (25%), running (20%) and swimming (18%). Gymnastics and swimming seem to reduce LBP significantly. Our results show a falling interest in participating in sports activities over time, with 68% of the subjects being members of an athletic association previously, but only 29% currently. Women were more physically inactive during leisure time, probably because of their dual role. Logistic regression analysis indicates that physical activity is related to a long school education, high social class and regular sports activity over time.  相似文献   
104.
Summary This study evaluates local variations of the cerebral vasomotor responses to hypercapnia and haemorrhagic hypotension in a pig model. Four laser Doppler flow probes were used in each pig. There was considerable variation in laser Doppler signals between the four probes in baseline recordings. The increases in flow after CO2 administration in 7 pigs had a mean coefficient of variation of 0.43 ± 0.31, and the flow changes after blood loss in another 7 pigs had a mean coefficient of variation of 0.45 ± 0.34. The range of flow changes within each animal was large; the probe with the highest CO2 response showed on the average a 273% ± 157% larger CO2 response than the probe with the lowest CO2 response. Correspondingly, the probe with the best preserved blood flow after blood loss had on the average a flow value of 93% ± 12% of the baseline value, while the probe that changed most with haemorrhage had a flow value of 44% ± 24% of the baseline value. Single laser Doppler recordings have been used for the monitoring of cerebral blood flow in neurosurgical critical care, but our results suggest that a single laser Doppler flow probe is not an adequate method to monitor vasoreactivity in neurosurgical patients because flow signals from one probe may be unrepresentative for other sites in the brain.  相似文献   
105.
OBJECTIVE: To report on the high incidence of anatomical variants of the origin and course of the internal spermatic vein (ISV) discovered at the time of percutaneous embolization of left varicoceles in a pediatric population. METHODS: We reviewed retrospectively the 65 cases of left varicocele treated by percutaneous embolization (grade II and III) in our institution between 1990 and 2000. The course of the left renal vein (LRV), the origin of the ISV, and the number of ISVs and their pathway were recorded in all cases, according to the B?hren classification. RESULTS: In 37/65 (57%), the ISV was single and arose from a normal LRV (type I). The following variants were encountered: type V--circumaortic LRV 9/65 (14%); type IVb--intrarenal origin of ISV 8/65 (12%); type II--multiple ISV 5/65 (8%); and pelvic collaterals 6/65 (9%). CONCLUSION: Venous anatomical variants are frequently encountered (43%) at the time of left varicocele embolization in children. Such variants often impose some adjustments to the technique of embolization and, at times, hamper the procedure.  相似文献   
106.
The volumes of distribution of many acidic drugs have been shown to be close to that of their binding protein, i.e. serum albumin. The distribution of basic drugs mainly bound to alpha 1-acid glycoprotein (AAG) can be questioned with respect to its dependency upon the distribution of this plasma protein. So, a pharmacokinetic study was performed in 7 subjects with human 125I-labelled alpha 1-acid glycoprotein. The steady-state volume of distribution was found to be 5.37 +/- 0.82L. The central volume was 3.23 +/- 0.33L, close to that of plasma volume and the peripheral volume was 2.14 +/- 0.63L. These data allowed the establishment of an equation giving access to the volume of distribution of a basic drug by relating its unbound fraction to physiological distribution of alpha 1-acid glycoprotein. The values yielded by this equation show that the actual and calculated volumes of distribution of basic drugs mainly bound to AAG are discrepant. This protein is thus not the main factor controlling the distribution of basic drugs within the body.  相似文献   
107.
108.
OBJECTIVE: The combination of mifepristone and misoprostol is an established method for induction of early first trimester abortion, but there is no consensus about the best evaluation of treatment outcome. We assessed endometrial thickness, determined by ultrasound and serum-human chorionic gonadotropin (s-hCG) as markers of successful management. METHODS: Prospective trial involving 255 women, with a gestation of 62 days or less, who were to undergo medical abortion. In addition to our established routines of performing clinical and ultrasound examinations, we also determined the s-hCG level prior to treatment and at follow-up. RESULTS: Of the 255 subjects treated during the study, 20 (7.8%) were lost to follow-up. The overall complete abortion rate was 94.0%. Fourteen subjects required vacuum aspiration, nine of them prior to the scheduled follow-up and five thereafter. None of the pregnancies were ongoing. A decrease of 99% in s-hCG levels was noted in 99% of the women, when levels determined prior to mifepristone intake and those measured 15-71 days post-abortion were compared. CONCLUSION: This study confirms that s-hCG levels drop sharply after medical abortion. To assess the completeness of medical abortion, we recommend that clinical examination to be combined with determination of s-hCG. Ultrasonography should be carried out only when indicated.  相似文献   
109.
110.
Neuropathological studies were carried out on 180 human immunodeficiency virus-seronegative intravenous drug addicts. The findings in victims of acute heroin intoxication (n = 116) were congestion (99.1%), capillary engorgement (68.1%), and/or perivascular bleeding (68.1%) – hemodynamic processes attributable to toxic primary respiratory failure. In a high percentage of these cases (88%), cerebral edema was also present. In 18 cases of acute heroin intoxication who survived for periods of hours or days, the sole postmortem finding was ischemic nerve cell damage, resembling that typically seen in systemic hypoxia. Semiquantitative analysis revealed nerve cell loss in the hippocampal formation and/ or Purkinje cell layer in 26% of the 162 chronic drug abusers. By contrast, in nearly 80% of these cases, the hippocampus showed enhanced expression of glial fibrillary acid protein by astrocytes and/or a proliferation of microglia, demonstrated by CD68 expression. Since such reactive processes are produced by primary neuronal damage, it can be assumed that chronic intravenous drug abuse results in obviously ischemic nerve cell loss. This could be demonstrated in the hippocampus, but it must also occur throughout the whole brain. The demonstration of ischemic nerve cell damage and neuronal loss or secondary reactive alterations has not been described previously. Received: 31 March 1995 / Revised, accepted: 27 November 1995  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