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   1817921篇
  免费   146332篇
  国内免费   3287篇
耳鼻咽喉   24467篇
儿科学   59394篇
妇产科学   50657篇
基础医学   255999篇
口腔科学   55280篇
临床医学   159842篇
内科学   360459篇
皮肤病学   38672篇
神经病学   149927篇
特种医学   72045篇
外国民族医学   501篇
外科学   273863篇
综合类   41780篇
现状与发展   4篇
一般理论   725篇
预防医学   144698篇
眼科学   40769篇
药学   134757篇
  2篇
中国医学   3593篇
肿瘤学   100106篇
  2019年   15073篇
  2018年   20928篇
  2017年   16138篇
  2016年   17328篇
  2015年   20171篇
  2014年   28052篇
  2013年   41053篇
  2012年   57717篇
  2011年   60741篇
  2010年   34954篇
  2009年   32934篇
  2008年   55908篇
  2007年   59066篇
  2006年   59006篇
  2005年   57633篇
  2004年   56559篇
  2003年   53440篇
  2002年   50622篇
  2001年   79628篇
  2000年   82077篇
  1999年   70082篇
  1998年   19902篇
  1997年   18056篇
  1996年   17860篇
  1995年   17371篇
  1994年   16358篇
  1993年   15469篇
  1992年   57554篇
  1991年   55808篇
  1990年   54454篇
  1989年   52708篇
  1988年   48972篇
  1987年   48171篇
  1986年   45771篇
  1985年   44313篇
  1984年   33174篇
  1983年   28535篇
  1982年   16861篇
  1981年   15054篇
  1979年   31245篇
  1978年   21645篇
  1977年   18217篇
  1976年   17069篇
  1975年   18066篇
  1974年   21964篇
  1973年   21165篇
  1972年   19255篇
  1971年   18107篇
  1970年   16687篇
  1969年   15639篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The physiopathology of postoperative hypoxia has been analysed, the cause being identified in the worsening of the V/Q ratio consequent on the reduction in CFR. By increasing CFR, CPAP reduces the superimposition of Tidal Volume and Closing Volume, thus reducing dysventilated zones and thereby improving the V/Q ratio and oxyaemia. With these premises, 18 patients undergoing cholecystectomy were examined; 8 of them were treated in the postoperative period with CPAP at pre-established intervals. The results confirm its effectiveness in terms of PaO2 improvement and the need for constant administration, considering that the benefits are lost when the patient is disconnected from the mask.  相似文献   
992.
The clinical profile of tropical spastic paraparesis (TSP), described in scattered tropical and subtropical territories over the past 30 years, has been more clearly defined since the discovery of its direct association with human T lymphotropic virus type 1 (HTLV-1). A chronic disease of adults, commoner in women, it usually presents as a progressive spastic paraparesis with sphincter disturbance, sometimes with backache and lower limb sensory disorder. Most cases are chair-bound within 10 years. Histology reveals a chronic lymphocytic meningomyelopathy, predominantly in the spinal cord, together with long tract demyelination and hyalinoid thickening of the media and adventitia of small blood vessels. Geographical areas of high prevalence of TSP are known in the Caribbean, South America, South Africa, southern Japan, the Seychelles and probably in India, and it is sparsely endemic elsewhere. The virus appears to exist within lymphocytes for long periods. Vertical transmission occurs postnatally, and sexual and transfusion infection are also recognized, but much remains to be clarified regarding its pathogenesis and epidemiology.  相似文献   
993.
994.
995.
In a randomized study the clinical and bacteriologic effectiveness of imipenem was compared with the classical combination of netilmicin with clindamycin in patients who had surgery for an intraperitoneal infection, localized or generalized, with positive bacteriologic findings of the specimen taken at surgery. Excluded were all patients who received other antibiotics before surgery, or who died within 3 days after antibiotic therapy was started. Imipenem was given at a dose of 500 mg t.i.d., clindamycin 600 mg t.i.d., and netilmicin according to serum levels. The diagnoses ranged from postoperative peritonitis, gallbladder empyema, perforated gastroduodenal ulcer, small bowel perforation with and without obstruction, and perforated appendicitis to perforation of the colon. The bacteriologic work-up included examination of the primary specimen (aerobic and anaerobic), the urine, feces, and serologic testing for Candida albicans once or twice a week and after the course of antibiotic therapy. In addition, pH measurements of abscesses and drainage fluids were performed. Ninety-three patients entered the study. Forty-seven patients were treated with imipenem (test group), and 46 patients were treated with the combination therapy (control group). The two groups did not show significant differences in age, sex, diagnostic groups, risk factors, primary bacteriology, and duration of therapy (mean: 6.7 days). Thirty-eight patients (80.9%) treated with imipenem were cured, six patients (12.8%) were improved, and there were three (6.4%) failures. The respective numbers for the control group were 31 (67.4%), 10 (21.7%), and 5 (10.9%). The mean duration of hospitalization was 19 days for the test group and 24.5 days for the control group. There were four wound infections in the test group and 11 wound infections in the control group. Imipenem is at least as effective in the adjuvant therapy of intra-abdominal infections as the combination of netilmicin with clindamycin.  相似文献   
996.
997.
Three evaluation instruments (global, check-list, and criterion referenced) were used by experienced and inexperienced examiners to evaluate dental sealant end products on 40 extracted teeth. Intra- and interexaminer reliabilities were measured. Experienced examiners achieved higher intrarater reliabilities with all three evaluation instruments than did inexperienced examiners. The highest intraexaminer agreement for all examiners occurred with use of the global evaluation. The highest interexaminer reliability was achieved with the second use of the criterion-referenced evaluation by the experienced examiner. Interexaminer reliability was improved for both types of examiners with the criterion-referenced evaluation.  相似文献   
998.
For a variety of reasons, the past few years have brought about a tremendous emphasis on conditions affecting the temporomandibular joint and associated structures. Although important advances are being made relative to the diagnosis and treatment of these conditions, a myriad of problems remain for the practitioner who tries to sort through the literature or who attends courses in order to determine a means for properly diagnosing and treating these patients. This article attempts to develop correlations between certain clinical and radiographic findings documented by histologic evaluation as a beginning guide to more sound diagnosis.  相似文献   
999.
Two cases of distal radioulnar joint (DRUJ) disruption and diastasis secondary to distal radial fractures were associated with displacement of the ulnar styloid and extensor carpi ulnaris (ECU) into the DRUJ. Both cases had a palpable empty ECU tendon sulcus. In one case surgical exploration revealed that the ulnar styloid, triangular fibrocartilage, and extensor carpi ulnaris tendon had dislocated into the DRUJ as a unit. The end result was good. In the second case lack of recognition and reduction of the ECU tendon and ulnar styloid led to persistent subluxation and diastasis. The end result was poor. Early recognition of the dislocation of the ulnar and ECU into the DRUJ and their significance may avoid poor results.  相似文献   
1000.
Previously, we reported that short term administration of a highly potent GnRH agonist (GnRHa) for 1 month to patients with polycystic ovarian disease (PCO) resulted in complete suppression of ovarian steroidogenesis without measurable effects on adrenal steroid production. This new study was designed to evaluate the effects of long term GnRHa administration in PCO patients with respect to their hormone secretion patterns and clinical responses. Eight PCO patients and 10 ovulatory women with endometriosis were treated daily with sc injections of [D-His6-(imBzl]),Pro9-NEt]GnRH (GnRHa; 100 micrograms) for 6 months. Their results were compared to hormone values in 8 women who had undergone bilateral oophorectomies. In response to GnRHa, PCO and ovulatory women had rises of serum LH at 1 month, after which it gradually declined to baseline. In both groups FSH secretion was suppressed throughout treatment. Serum estradiol, estrone, progesterone, 17-hydroxyprogesterone, androstenedione, and testosterone levels markedly decreased to values found in oophorectomized women by 1 month and remained low thereafter. In contrast, serum pregnenolone and 17-hydroxypregnenolone were partially suppressed, and dehydroepiandrosterone, dehydroepiandrosterone sulfate, and cortisol levels did not change. Clinically, hyperplastic endometrial histology in three PCO patients reverted to an inactive pattern, and proliferative endometrium in two other PCO patients became inactive in one and did not change in the other. Regression of proliferative endometrial histology occurred in all ovulatory women. Vaginal bleeding occurred in all women studied during the first month of GnRHa administration, after which all but one PCO patient became amenorrheic. Hot flashes were noted by all ovulatory women and by four of eight PCO patients. All PCO patients noted subjective reduction of skin oiliness, and five had decreased hair growth. We conclude that in premenopausal women: 1) chronic GnRHa administration results in apparently complete persistent suppression of ovarian steroid secretion; 2) adrenal steroid secretion is not influenced directly or indirectly; and 3) its use may be helpful in the treatment of endometrial hyperplasia and ovarian androgen excess in women with PCO.  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