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   405篇
  免费   15篇
  国内免费   17篇
儿科学   12篇
基础医学   29篇
口腔科学   2篇
临床医学   24篇
内科学   66篇
皮肤病学   12篇
神经病学   6篇
特种医学   104篇
外科学   109篇
综合类   7篇
预防医学   4篇
药学   32篇
中国医学   1篇
肿瘤学   29篇
  2023年   1篇
  2022年   1篇
  2021年   4篇
  2020年   2篇
  2019年   1篇
  2018年   3篇
  2017年   1篇
  2016年   7篇
  2015年   4篇
  2014年   5篇
  2013年   3篇
  2012年   9篇
  2011年   10篇
  2010年   5篇
  2009年   15篇
  2008年   23篇
  2007年   30篇
  2006年   17篇
  2005年   10篇
  2004年   17篇
  2003年   11篇
  2002年   7篇
  2001年   7篇
  2000年   9篇
  1999年   10篇
  1998年   17篇
  1997年   25篇
  1996年   13篇
  1995年   15篇
  1994年   14篇
  1993年   9篇
  1992年   7篇
  1991年   5篇
  1990年   7篇
  1989年   17篇
  1988年   20篇
  1987年   13篇
  1986年   10篇
  1985年   6篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
  1980年   9篇
  1979年   2篇
  1978年   5篇
  1977年   9篇
  1976年   6篇
  1975年   5篇
  1969年   1篇
排序方式: 共有437条查询结果,搜索用时 15 毫秒
1.
In the last years, granulocyte and granulocyte-macrophage colony-stimulating factors (G-CSF and GM-CSF) are being increasingly used and several cutaneous eruptions have been reported in relation to these treatments. In 1991 Horn et al. described three patients with maculopapular eruption that paralleled the time of infusion of GM-CSF. Two of the cases showed an increase in the number and size of macrophages in the biopsy specimen. Since then, several cases have been reported showing this histopathological alteration that has been considered characteristic of reaction to G-CSF or GM-CSF. Although maculopapular eruption with enlarged macrophages can appear after chemotherapy treatment, we have found that the presentation of this eruption after the beginning of cytokine treatment is suggestive of the involvement of G-CSF and GM-CSF in the eruption. We described eight cases of patients treated with G-CSF or GM-CSF that developed maculopapular eruptions with enlarged macrophages.  相似文献   
2.
3.
Oocyte morphology predicts outcome of intracytoplasmic sperm injection   总被引:10,自引:14,他引:10  
To examine the influence of cytoplasmic morphology on the success rate of intracytoplasmic sperm injection (ICSI), the morphology of 837 metaphase II oocytes was assessed after cumulus stripping. The main abnormalities detected were excessive granularity, cytoplasmic inclusions such as vacuoles, smooth endoplasmic reticulum clustering and refractile bodies. Microinjection was performed in 538 oocytes with normal cytoplasm, 142 out of 161 with excessive granularity and 112 out of 138 with cytoplasmic inclusions. Very poor oocytes were not injected. No difference was found in fertilization rate. The embryos achieved cleaved normally and a similar number of good quality embryos among the three groups was noted. The outcome of transfer of embryos derived solely from normal oocytes (group A: 72 patients, 183 embryos) was compared with those from oocytes with cytoplasmic abnormalities (group B: 34 patients, 85 embryos). In group A, 17 clinical pregnancies (24% per patient, implantation rate 10%) were established. In group B, only one clinical pregnancy (3% per patient, implantation rate 1%) was established, from the transfer of embryos derived from oocytes with homogeneous granularity of the cytoplasm. No pregnancy resulted following the transfer of embryos from eggs with cytoplasmic inclusions. The difference was statistically significant. The outcome of ICSI is dependent on the quality of the oocytes retrieved. Normal fertilization and early embryo development were achieved in oocytes with abnormal cytoplasm morphology, but the resulting embryos failed to demonstrate the same implantation potential as those derived from oocytes with normal cytoplasm.   相似文献   
4.
Posterior and anterior heights, cross-sectional area and shape were measured for all the intervertebral discs in four spines from elderly human cadavers. Disc height was a minimum at the T4-5 level; thoracic discs were less wedge-shaped than those in the cervical and lumbar regions. Cross-sectional area increased from the cranial to caudal extremity; at the L5-S1 level the nucleus pulposus occupied a high proportion of this area. Cervical discs tended to have an elliptical cross-sectional shape, thoracic discs were more circular and lumbar discs tended to have an elliptical cross-section which was flattened or re-entrant posteriorly. This shape distribution was quantified by defining a shape index which had a maximum value of 1 for a circular cross-section. Orientations of the reinforcing fibres in the outer lamellae of the anterior annulus fibrosus were measured from 27 discs by X-ray diffraction. For these measurements, C3-4, T7-8 and L2-3 were chosen as representative of cervical, thoracic and lumbar discs. The fibre tilt, with respect to the axis of the spine, was significantly less in the cervical discs (at 65 degrees) than in the thoracic and lumbar discs (about 70 degrees). These findings are interpreted in relation to differing functional requirements and possible mechanisms of failure in the cervical, thoracic and lumbar regions of the spine in the light of current knowledge on the biomechanics of the intervertebral disc.  相似文献   
5.
Cellular immunity against multiple Hepatitis C virus (HCV) proteins is observed in patients acutely infected with HCV most of whom later resolve infection. We wished to assess humoral immunity in patients infected with HCV 1a or 1b genotypes in relation to viral load using plasma samples from HCV-infected individuals and a panel of peptides representing immunodominant epitopes of HCV structural and nonstructural proteins. Plasma from HCV 1a- and 1b-infected patients, respectively, were divided into two groups: patients with low viral load (<==100,000 RNA copies/ml) and patients with high viral load (>/=10,000,000 RNA copies/ml). The antigens were peptides representing epitopes from immunodominant regions of HCV core, E2, NS3, and NS4 proteins, as well as the hypervariable (HVR) epitopes in E2 from genotypes 1a and 1b. Individuals infected with HCV 1a evoked a stronger immune response to many immunodominant epitopes of HCV relative to individuals infected with HCV 1b. Moreover, among individuals infected with HCV 1a, those with low viral loads mounted significantly greater responses against these epitopes than did individuals with high viral loads. Our observations demonstrate that quantitatively different antibody responses are elicited against HCV depending on the genotype of infecting virus, and suggest that humoral immunity directed against multiple immunodominant epitopes in HCV 1a-infected individuals may help lower viral load in vivo.  相似文献   
6.
Kuypers  FA; Lubin  BH; Yee  M; Agre  P; Devaux  PF; Geldwerth  D 《Blood》1993,81(4):1051-1057
In the human erythrocyte membrane phosphatidylcholine and sphingomyelin reside mainly in the outer leaflet, whereas the aminophospholipids, phosphatidylethanolamine and phosphatidylserine, are mainly found in the inner leaflet. Maintenance of phospholipid asymmetry has been assumed to involve interactions between the aminophospholipids and the membrane skeleton, in particular spectrin. To investigate whether spectrin contributes to maintaining the phospholipid transbilayer distribution and kinetics of redistribution, we studied erythrocytes from hereditary spherocytosis patients whose spectrin levels ranged from 34% to 82% of normal. The phospholipid composition and the accessibility of membrane phospholipids to hydrolysis by phospholipases were in the normal range. Spin-labeled phosphatidylserine and phosphatidylethanolamine analogues that had been introduced into the outer leaflet were rapidly transported at 37 degrees C to the inner leaflet, whereas the redistribution of spin-labeled phosphatidylcholine was slower. The kinetics of transbilayer movement of these spin-labeled phospholipid in all samples was in the normal range and was not affected by the level of spectrin. Although these erythrocyte membranes contained as little as 34% of the normal level of spectrin and were characterized by several physical abnormalities, the composition, distribution, and transbilayer kinetics of the phospholipids were found to be normal. We therefore conclude that spectrin plays, at best, only a minor role in maintaining the distribution of erythrocyte membrane phospholipid.  相似文献   
7.
STUDY OBJECTIVE--Polarographic oxygen sensitive electrodes can be used to measure tissue oxygen pressures on the surface of the beating heart. The purpose of the study was to clarify the significance of these PO2 determinations. DESIGN--Changes in left ventricular surface oxygen pressures, subendocardial or subepicardial wall functions (ultrasonic dimension technique), and blood flow (radioactive microsphere technique) were correlated during different degrees of acute coronary artery stenoses in pigs. EXPERIMENTAL MATERIAL--19 anaesthetised open chest pigs, 28-40 kg body weight, were studied during different degrees of constriction of the left anterior descending artery which did not influence overall left ventricular function or irreversibly damage the myocardium. MEASUREMENTS AND MAIN RESULTS--Highly significant (p less than 0.001) correlations (each % delta) were obtained for surface tissue oxygen pressures (y) with subepicardial (y = 0.002 e 0.10x; r = 0.89) and subendocardial (y = 1.44 e 0.04x; r = 0.98) blood flow values, as well as with subendocardial function (y = 82.4 + 0.22x; r = 0.89); a significant correlation was also obtained for subendocardial function (y) with subendocardial blood flow (y = 66.0 + 0.28x; r = 0.69). However, no significant correlation was obtained for polarographic tissue PO2 with subepicardial segment function, indicating that regional function was maintained when tissue PO2 recordings were not much above 0 kPa and when blood flow was reduced by 25 to 30%. CONCLUSIONS--Oxygen pressures of the superficial layers of the left ventricle are relatively high at normal values of oxygen consumption but decrease rapidly if blood supply is reduced. Regional wall function is preserved at low oxygen pressures. Polarographic surface PO2 electrodes hence can be used to study influences of experimental interventions on oxygenation of the normally perfused and of the moderately ischaemic myocardium.  相似文献   
8.
9.
10.
Factor V deficiency has been identified in 8 of 8 patients 7--20 yr of age, with Philadelphia-positive (Ph1+) chronic myelogenous leukemia (CML). In these 8 patients, factor V deficiency was not due to hepatic dysfunction, factor V inhibitors, or disseminated intravascular coagulation. In 3 patients, factor V activity rose 10%--12% (0.10--0.12 U/ml) after the infusion of 28--31 ml/kg body weight of fresh frozen plasma (FFP). The rise persisted less than 14 hr. The mean measured postinfusion rise in factor V was 18% of the expected rise calculated from the volume of FFP infused in the patients' plasma volume. In 4 patients, a small transient rise in factor V activity occurred after splenectomy or plateletpheresis. Factor V deficiency was completely corrected after a marked reduction in bone marrow cellularity in 2 patients with Ph1+ CML treated with extensive chemotherapy, total body irradiation, and bone marrow transplantation. Factor V deficiency was retrospectively observed in 6 of 20 patients, ages 20--80 yr, with Ph1+ CML and 3 of 6 patients with other myeloproliferative disorders. The factor V deficiency appears to be associated with the large myeloid- megakaryocytic cell mass characteristic of CML and other myeloproliferative disorders.  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