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   7153篇
  免费   581篇
  国内免费   11篇
耳鼻咽喉   16篇
儿科学   193篇
妇产科学   136篇
基础医学   821篇
口腔科学   116篇
临床医学   902篇
内科学   1473篇
皮肤病学   70篇
神经病学   585篇
特种医学   358篇
外科学   1284篇
综合类   239篇
一般理论   6篇
预防医学   715篇
眼科学   60篇
药学   383篇
中国医学   6篇
肿瘤学   382篇
  2022年   52篇
  2021年   99篇
  2020年   70篇
  2019年   110篇
  2018年   135篇
  2017年   91篇
  2016年   113篇
  2015年   107篇
  2014年   129篇
  2013年   271篇
  2012年   344篇
  2011年   381篇
  2010年   213篇
  2009年   160篇
  2008年   296篇
  2007年   324篇
  2006年   342篇
  2005年   279篇
  2004年   324篇
  2003年   284篇
  2002年   282篇
  2001年   256篇
  2000年   252篇
  1999年   229篇
  1998年   96篇
  1997年   91篇
  1996年   83篇
  1995年   54篇
  1994年   64篇
  1993年   64篇
  1992年   177篇
  1991年   186篇
  1990年   166篇
  1989年   159篇
  1988年   116篇
  1987年   128篇
  1986年   115篇
  1985年   127篇
  1984年   97篇
  1983年   83篇
  1982年   53篇
  1981年   48篇
  1980年   44篇
  1979年   69篇
  1978年   63篇
  1977年   44篇
  1976年   36篇
  1974年   44篇
  1973年   42篇
  1969年   35篇
排序方式: 共有7745条查询结果,搜索用时 15 毫秒
991.
Surgery in a geriatric population.   总被引:4,自引:1,他引:3  
A prospective audit of 1111 general surgical procedures undertaken on 1040 elderly patients (over 64 years) revealed a mortality of 3.5% in potentially viable patients. Aged patients (over 74 years) had twice the mortality of old patients (65-74 years). Emergency surgery carried a sevenfold risk factor which is greater than is usually described. Of those patients who died (n = 56) 20 had a laparotomy for surgically incurable disease. Although the four grades of surgeon achieved similar mortality rates (range 4-5.8%), senior surgeons performed more major procedures (Consultants, 40%; SHOs, 19%). There was a low supervision rate of SHOs (37/100 overall, and 9/19 major cases). Of the 26 patients dying from medical disorders 17 had a previous history of that disorder, and only nine of these patients were admitted to our high dependency care unit. We conclude that mortality rates in the elderly could be improved by encouraging elective surgery and avoiding diagnostic laparatomy in patients with incurable surgical disease. We also suggest that no inexperienced surgeon should operate unsupervised on any elderly patient who is in ASA category 4 or 5, or who undergoes major or intermediate surgery. Further, all elderly patients in ASA category 4 or 5, or those with previous medical problems who have major emergency procedures should be managed postoperatively in a high dependency care unit.  相似文献   
992.
OKT3, a murine monoclonal antibody, is a potent, specific immunosuppressive agent used in solid-organ transplantation both as an adjunct during induction therapy and for treatment of steroid-resistant graft rejection. Minor, self-limiting ocular complications are often seen with this drug, of which conjunctivitis is the most common, occurring in approximately three-quarters of patients. We describe the more serious and previously unreported complication of diffuse anterior scleritis, which developed on the fifth day of OKT3 therapy in a 47-year-old man who had undergone cadaveric renal transplantation. Despite continuation of OKT3 treatment the scleritis resolved rapidly with increased dosages of prednisone.  相似文献   
993.
An enzyme-linked immunosorbent assay specific for flagellum type (a or b) of Pseudomonas aeruginosa was used to detect serum immunoglobulin antibodies in 98 random outpatients and 14 colonized cystic fibrosis patients. Antibodies were detected to both types of flagella in addition to M-2 lipopolysaccharide. Titers to both flagellar antigens (FlAg) were 10 to 100 times higher in cystic fibrosis patients than in random outpatients of a comparable age group. Mean antibody titers against b-type FlAg were 454 for outpatients (ages newborn to 21 years), whereas the mean titer for cystic fibrosis patients (ages 6 to 21 years) was 51,520. Titers against a-type FlAg were generally lower, with mean outpatient titers of 68 and mean cystic fibrosis patient titers of 34,323. Differences were also seen in antibody titer against M-2 lipopolysaccharide, but these differences did not correspond to M-2 FlAg titers. In 98 random outpatients (ages newborn to 86 years), FlAg titers generally increased with age. To demonstrate further specificity of the enzyme-linked immunosorbent assay for flagellum antibody, Western blots were performed with selected high-titer cystic fibrosis patient sera. Sera that had a high titer (greater than 25,600) for b- or a-type FlAg showed a corresponding reactive band. These results demonstrate that flagellum antibodies are produced in humans in response to P. aeruginosa infection.  相似文献   
994.
Computed tomographic detection of nonbeta pancreatic islet cell tumors   总被引:6,自引:0,他引:6  
  相似文献   
995.
996.
Other than the potentially therapeutic bronchodilatory influences of marihuana, very little is known of its biologic effects on the lung. To evaluate this problem, alveolar macrophages were harvested from rats by bronchopulmonary lavage and incubated in vitro with Staphylococcus albus and marihuana smoke of standardized 2.2-percent tetrahydrocannabinol content in graded amounts. After three hours, control alveolar macrophages inactivated 78.0 +/- 5.0 percent of the staphylococcal challenge. There was a dose-dependent depression of alveolar macrophage bactericidal activity, with 66.7 +/- 7.1 percent, 23.7 +/- 7.0 percent, 20.5 +/- 7.0 percent, and 11.4 +/- 7.6 percent of the bacteria killed following exposures to 2 ml, 4 ml, 6 ml, or 8 ml of marihuana smoke, respectively. Differential filtration of marihuana smoke revealed that the alveolar macrophage cytotoxin was present in the gas phase of the smoke and was water-soluble. Studies on purified tetrahydrocannabinol and on tetrahydrocannoabinol-extracted marihuana revealed that the impairment in alveolar macrophage function was not related to the psychomimetic or bronchodilatory components of marihuana.  相似文献   
997.
In August-October 1980, a sudden increase occurred in the number of cases of jaundice reported among residents of a rural, agricultural section of Lancaster County, Pennsylvania. Investigation confirmed the cases as hepatitis A and showed that the outbreak was associated with consumption of water from a water fountain in a hardware store and water from the adjacent family home, both of which came from a well contaminated with feces. A total of 49 cases occurred from August 11 to October 21 in store customers, employees, family members, and persons visiting the family residence. Unusual features of the outbreak included an epidemic curve with two peaks, a very high attack rate in susceptibles at highest risk (greater than 90%), a high proportion of cases with jaundice (85%), absence of asymptomatic cases, and a high male to female ratio due to the makeup of the group at risk.  相似文献   
998.
999.
Changes in normal polymorphonuclear leucocyte (PMN) motility after membrane-binding and internalisation of IgG aggregates (a model of soluble immune complexes) have been studied by the micropore filter assay. The results have confirmed that IgG aggregates stimulate as well as inhibit PMN chemotaxis. These effects are dependent on the size and concentration of the IgG aggregates in solution as well as the length of time of incubation. Stimulated chemotaxis was observed in a small subset of the whole PMN population which was apparent only when cell distribution through the filters was analysed. These results indicate the need for caution when drawing conclusions about PMN function from results obtained by these assay techniques.  相似文献   
1000.
Plasma fatty acid profiles of 33 critically ill surgical patients receiving fat-free parenteral nutrition were examined at weekly intervals up to 28 days. While plasma total fatty acid concentration remained relatively constant and within the normal range, marked compositional alterations were apparent. Levels of linoleate (18:2ω6), the major essential fatty acid in man, fell below normal values (754 ± 259 μg/ml) in 67 percent of patients within 1 week after cessation of oral intake. Decreases in other ω6 unsaturated fatty acids, derived from linoleate, were also apparent. In contrast, gradual increases were observed in levels of endogenously synthesized fatty acids, palmitate (16:0), palmitoleate (16:1) and oleate (18:1ω9). A fatty acid unique to essential fatty acid deficiency, 5,8,11 eicosatrienoate (20:3ω9), appeared in 25 percent of the patients during the first week and in all patients by the third week of study. Considering the rapid appearance and progression of these bio-chemical changes, early initiation of linoleate supplementation appears justified to forestall the development of related clinical sequelae.  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