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   3048篇
  免费   101篇
耳鼻咽喉   9篇
儿科学   96篇
妇产科学   73篇
基础医学   189篇
口腔科学   65篇
临床医学   689篇
内科学   846篇
皮肤病学   100篇
神经病学   86篇
特种医学   3篇
外科学   335篇
综合类   33篇
一般理论   18篇
预防医学   194篇
眼科学   22篇
药学   328篇
肿瘤学   63篇
  2016年   37篇
  2015年   43篇
  2014年   42篇
  2013年   81篇
  2012年   23篇
  2011年   15篇
  2010年   86篇
  2009年   100篇
  2008年   29篇
  2007年   26篇
  2006年   39篇
  2005年   13篇
  2003年   20篇
  2002年   17篇
  2001年   53篇
  2000年   20篇
  1999年   101篇
  1998年   128篇
  1997年   181篇
  1996年   170篇
  1995年   134篇
  1994年   111篇
  1993年   109篇
  1992年   111篇
  1991年   90篇
  1990年   84篇
  1989年   84篇
  1988年   85篇
  1987年   67篇
  1986年   64篇
  1985年   47篇
  1984年   52篇
  1983年   47篇
  1982年   42篇
  1981年   55篇
  1980年   38篇
  1979年   36篇
  1978年   35篇
  1977年   31篇
  1976年   33篇
  1975年   23篇
  1972年   14篇
  1971年   19篇
  1959年   55篇
  1958年   69篇
  1957年   55篇
  1956年   57篇
  1955年   50篇
  1954年   60篇
  1948年   25篇
排序方式: 共有3149条查询结果,搜索用时 0 毫秒
101.
OBJECTIVE: To identify the characteristics of neonates exposed to drugs in utero but admitted to the normal newborn nursery because of apparent good health. DESIGN: Retrospective evaluation with chart review of toxicology screening tests sent from a normal newborn nursery. SETTING: Newborn service in an urban hospital. PARTICIPANTS: Fifty newborns with positive drug screening results. MAIN OUTCOMES: Frequency of positive results and assessment of demographic features and neonates' clinical features. RESULTS: 43 (86%) of the apparently healthy newborns tested positive for cocaine. The results of simultaneous or proximate drug testing of mothers and their newborns were discordant in 11 (22%) cases. CONCLUSIONS: Neonates with in utero drug exposure often are born with few or no signs of abnormality and are admitted to the normal newborn nursery.  相似文献   
102.
103.
Summary. Knee haemarthroses are very common in the haemophiliac and often, despite infusion of the missing coagulation factor, synovitis develops. The warm swollen joint is maintained in the most comfortable position for the haemophiliac: flexion. Ambulation is achieved by planterflexion of the ankle joint and toewalking. As the chronic synovitis persists, the range of movement of the knee is affected, with loss of full extension. Development of radiological degenerative signs develop. The quadriceps muscle usually weaken due to disuse, but the hamstrings are active in maintaining the flexion of the joint. As the process continues, the tibia subluxes posteriorly on the condyles of the femur. The posterior capsule of the knee joint soon contracts, permanently limiting knee extension. A case is described on whom an Ilizarov device was used to gradually return the limb to a function position. This will allow the patient to complete his growth prior to a definitive orthopaedic procedure.  相似文献   
104.
We report a unique case of fluid penetration, 3 months after implantation, in the connector port of an automatic implantable Cardioverter defibrillator (ICD) with transvenous subcutaneous lead system. The patient had coronary artery disease and recurrent episodes of ventricular fibrillation, the fluid caused electrical signals interpreted as ventricular fibrillation by the device, which triggered shock delivery .  相似文献   
105.
Background. Several studies have documented cutaneous findings in neonates of various racial groups. Our purpose was to determine the frequency of birthmarks in Israeli neonates of Jewish and Arabic origin. Methods. A cohort of 1672 newborn infants under 96 hours of age were examined for the presence of birthmarks. Of these 841 (50·3%) were Jewish and 831 (49·7%) were Arab. The Jewish group was further subdivided into various ethnic groups according to parental ancestry. Results. Melanocytic brown lesions (Mongolian spots, congenital nevi, and cafe-au-lait spots), were more common in Arab infants. The vast majority of Jewish infants with Mongolian spots were of Asian or African ancestry. On the other hand, congenital melanocytic nevi were found only in Jewish infants of European ancestry. Vascular lesions (salmon patch and port-wine stain) in Arab neonates exhibited a female preponderance. Conclusions. Our data suggest that the prevalence of birthmarks in Israeli neonates is similar to the prevalence reported by others in white neonates.  相似文献   
106.
107.
The remarkable ability of the body to maintain balance is the result of central nervous system integration of sophisticated inputs from the vestibular, visual, and somatosensory systems. Strategies by patients with balance dysfunction are aphysiologic when their performance is relatively better on more difficult conditions of sensory conflict than on easier ones. Twenty-two aphysiologic patterns on computerized dynamic posturography were compared with age-matched normal and vestibular patterns. The aphysiologic group performed significantly better than the patients in the vestibular dysfunction group on the most difficult subtests of computerized dynamic posturography, conditions 5 and 6, yet significantly poorer on the easier subtests, conditions 1 through 4. In addition, patients in the aphysiologic group tended to show greater intertrial variability compared with patients in both normal and vestibular system dysfunction groups. A stepwise linear discriminant analysis was used to determine a set of conditions that had significant value in discriminating between the three patient groups. Case studies are presented to further illustrate the clinical usefulness of computerized dynamic posturography testing in the evaluation of patients suspected of having a functional component to their on-feet balance problems. (OTOLARYNGOL HEAD NECK SURG 1995;112:676-88.)  相似文献   
108.
We report a patient without immune compromise with infection of an automatic internal cardiac defibrilla- tor patch due to Aspergillus fumigatus presenting 8 years after implantation. The mechanism of infection was unknown, but symptoms began 1 month after laser uvulopalatopharyngoplasty was performed for sleep apnea. The patches were surgically removed and the patient was treated sequentially with amphotericin B and itraconazole. He remains without evidence of infection 12 months after the completion of therapy.  相似文献   
109.
A surface protein of Plasmodium berghei ookinetes, Pbs21, was expressed in a baculovirus-insect cell system in cell culture and in Heliothis virescens larvae. Groups of BALB/c mice received two intraperitoneal inoculations of either i) Tris-buffer or homogenized H. virescens larvae infected with wild-type baculovirus; ii) enriched, homogenized ookinetes, or Hi) homogenizedH. virescens larvae expressing recombinant Pbs21 (rPbs21). All animals immunized with ookinetes or with rPbs21 had high litres of antibodies (IgG isotype) that bound to native Pbs21. The large majority of antibodies in immune sera of both groups recognized the antigen under non-reducing but not under reducing conditions. The predominant IgG-sub-classes in mice immunized with ookinetes was IgGl and in mice immunized with rPbs21, the subclasses were IgGl and IgG2a. Immunization with rPbs21 reduced the infec-tivity of P. berghei to mosquitoes by 91% compared to a 99% reduction following immunization with ookinetes. This preliminary data indicate that rPbs21 expressed in this eukaryotic system induces a transmission-blocking immunity which is more effective than that achieved using rPbsll expressed in Escherichia coli (Matsuoka et al. 1994).  相似文献   
110.
We have investigated the influence of antithyroid drugs (methimazole and propylthiouracil) and sodium iodide on the expression of major histocompatibility (MHC) class II antigen expression in human and rat thyroid cells. While methimazole and propylthiouracil significantly inhibited lectin-induced MHC class II (HLA-DR) antigen in crude human thyroid monolayer preparations these drugs had no influence on gamma-interferon induction of class II antigens in similar cell preparations. Hence, antithyroid drugs probably had a direct effect on thyroid monolayer T cells which are known to effect the lectin induction of MHC class II antigen via T-cell secretion of the cytokine, gamma-interferon (IF). Sodium iodide, similarly, had no direct influence on human thyroid cell MHC class II antigen expression induced by gamma-IF. However, iodide significantly inhibited the gamma-IF-induced expression of MHC class II antigens in a proliferating rat thyroid cell clone derived from FRTL-5 cells (clone 1B-6). In the rat thyroid cell clone this antagonistic action appeared to be exerted via inhibition of TSH-induced proliferation. These data add further support to the multifactorial nature of the profound immunosuppressive influence of antithyroid drugs in autoimmune thyroid disease and experimental thyroiditis. In contrast, iodides may have a major, and often overlooked, influence on thyroid cell proliferation and antigen expression.  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