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   12996篇
  免费   640篇
  国内免费   53篇
耳鼻咽喉   76篇
儿科学   231篇
妇产科学   221篇
基础医学   1569篇
口腔科学   307篇
临床医学   836篇
内科学   3255篇
皮肤病学   182篇
神经病学   928篇
特种医学   525篇
外科学   2357篇
综合类   39篇
预防医学   264篇
眼科学   143篇
药学   1046篇
中国医学   25篇
肿瘤学   1685篇
  2023年   54篇
  2022年   100篇
  2021年   212篇
  2020年   119篇
  2019年   166篇
  2018年   177篇
  2017年   170篇
  2016年   219篇
  2015年   207篇
  2014年   283篇
  2013年   379篇
  2012年   529篇
  2011年   626篇
  2010年   348篇
  2009年   312篇
  2008年   611篇
  2007年   604篇
  2006年   585篇
  2005年   564篇
  2004年   687篇
  2003年   655篇
  2002年   639篇
  2001年   476篇
  2000年   464篇
  1999年   462篇
  1998年   194篇
  1997年   143篇
  1996年   145篇
  1995年   118篇
  1994年   130篇
  1993年   107篇
  1992年   284篇
  1991年   224篇
  1990年   249篇
  1989年   283篇
  1988年   274篇
  1987年   259篇
  1986年   230篇
  1985年   228篇
  1984年   133篇
  1983年   120篇
  1982年   66篇
  1981年   49篇
  1980年   50篇
  1979年   112篇
  1978年   67篇
  1977年   55篇
  1972年   53篇
  1971年   52篇
  1969年   61篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
71.
CA 125 is an antigen associated with non-mucinous epithelial ovarian cancer, which is defined by OC 125 antibody developed by immunizing ovarian cancer cells. We have produced two monoclonal antibodies, 130-22 and 145-9, by using the human lung adenocarcinoma cell line PC-9. Both 130-22 and 145-9 antibodies recognized CA 125 antigen. However, the binding sites seemed to be separate from those of OC 125. Testing by 9 immunoradiometric assays (IRMA), using different combinations of the 3 monoclonal antibodies 130-22, 145-9 and OC 125 demonstrated that the best standard curve for detecting CA 125 could be obtained by a "simultaneous sandwich" assay based on a mixture of 125I-labeled OC 125 and 130-22 or 145-9 coated beads. One-step IRMA, using 130-22 as a tracer and 145-9 as an immunoadsorbent, also showed good reproducibility and sensitivity for measuring CA 125. Antigens were detectable in the culture supernatants of PC-9 cells and 5 of 6 ovarian cancer and endometrial adenocarcinoma cells. These results indicate that one-step IRMA using 130-22 and 145-9 is useful for detecting CA 125 antigen.  相似文献   
72.
The CT findings of 19 children under 16 years of age with primary brain tumors in the cerebral hemisphere were investigated with special reference to the existence of cerebral hemiatrophy ipsilateral to the side of the tumor. "Ipsilateral cerebral hemiatrophy" was observed in four of 19 cases (21%). These included two cases with germinoma in the basal ganglia and two with low-grade astrocytoma in the frontal and occipital cortex. This peculiar CT finding was not specific to the location or histology of the tumor. The four cases were characterized by slow progression, which contrasted with the rapid progression of tumors shown in seven cases with a mass effect on CT.  相似文献   
73.
Treatment for delayed brain injury after pituitary irradiation is discussed. Six cases with delayed brain injury were treated with a combination of dexamethasone or betamethasone, with heparin, glycerol, dextran 40 and some vasodilators. Two cases with temporal lobe syndrome were treated in the early stages of brain injury for a period of over 12 months were almost completely cured, another two cases with chiasma syndrome were treated in the relatively late stages, showed a partial improvement. One case which was irradiated 120 GY during 13 years did not improve. The final case treated with steroids for a short period also resulted in failure and the patient underwent an operation for the removal of the necrotic mass three years after the radiotherapy. Steroid therapy started in the early stages of brain injury after irradiation for over the 12 months is thought to be effective. Heparin therapy was also effective in one out of three cases, but in one of the cases subarachnoid hemorrhage from a traumatic aneurysm occurred during the therapy. In an acute phase, showing edematous change of the injured brain, the administration of glycerol is also thought to be useful. But the effectiveness of the other medicines containing some vasodilators was obscure or doubtful. We propose the following: (1) A meticulous observation is essential for the patients who received high doses of irradiation to diagnose brain injury in the early reversible stage. (2) Steroids should be given immediately in this reversible stage of brain injury before the irreversible "necrosis" occurs. (3) Steroids should be maintained for a long period over 12 months.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
74.
The actions of the antiallergic agents, disodium chromoglycate (DSCG), tranilast and ketotifen, and of a calcium channel antagonist, nicardipine, and cross-reactivity among the agents were examined by observing the inhibition of45Ca uptake and histamine release in rat mast cells stimulated by antigen and compound 48/80 (comp. 48/80).
  1. All agents inhibited45Ca uptake and histamine release in mast cells stimulated by antigen. The inhibition of45Ca uptake by the antiallergic agents paralleled the inhibition of histamine release, while nicardipine inhibition of45Ca uptake was stronger than its inhibition of histamine release.
  2. The action of DSCG on45Ca uptake and histamine release was significantly decreased in cells stimulated with antigen and phosphatidylserine (PS), while tranilast inhibition of histamine release was not affected by the addition of PS despite a significant decrease in the inhibition of45Ca uptake.
  3. The inhibitory effect of DSCG and tranilast was significantly lower in mast cells stimulated by comp. 48/80 than in the cells stimulated by antigen.
  4. Tachyphylaxis was observed in cells re-exposed to DSCG and tranilast following previous exposure to the agents.
  5. Cross-reactivity was found between DSCG and tranilast.
  相似文献   
75.
Using a conditioning-test paradigm, we studied the recovery function of tibial nerve somatosensory evoked potentials (SEPs) conditioned by preceding peroneal nerve stimulation. The inter-stimulus intervals (ISIs) ranged from 0 to 400 msec, where 0 msec indicated simultaneous arrival of tibial and peroneal nerve volleys at the L1 spine. The recovery curve was W-shaped, showing two peaks of SEP suppression, maximum at 6 msec ISI (1st phase) and 50-75 ISI msec (2nd phase). In the 1st phase suppression, we found distinct differences in wave forms between 0-2 msec ISI and 4-6 msec ISI. At 0-2 msec ISI, P40-N50-P60 amplitude decreased and latencies shortened, while P31 and N35 were unchanged. At 4-6 msec ISI, all peaks, possibly excluding P31, were markedly depressed. We attribute the former change to an "occlusive effect" and the latter to an "inhibitory effect," each mediated via a central synaptic network between the two nerves. The attenuation of the 2nd but not the 1st phase suppression by peroneal nerve block distal to the stimulating electrodes provided evidence that the 2nd phase suppression resulted primarily from interfering afferent signals generated by peroneal nerve peripheral receptors, activated by foot movement.  相似文献   
76.
Positron emission tomography (PET) studies on regional cerebral glucose metabolism and [18F]fluorodopa uptake were performed on 3 patients with "pure akinesia without rigidity and tremors", 3 progressive supranuclear palsy (PSP) patients, and 5 patients with Parkinson's disease. The "pure akinesia" and PSP patients showed a marked decrease in glucose metabolism in the frontal cortex and striatum, and a decreased uptake of [18F]fluorodopa in the striatum. While the Parkinson's disease patients had a decreased uptake of [18F]fluorodopa in the striatum but no abnormality in the glucose metabolism. Magnetic resonance imaging (MRI) showed atrophy of the pretectum and dorsal pons in "pure akinesia" and PSP patients, but there was no such abnormality in the Parkinson's disease patients. As described above, patients with "pure akinesia" and PSP patients revealed similar findings on PET and MRI studies, while Parkinson's disease patients showed substantially different results.  相似文献   
77.
Regional cerebral blood flow (CBF) in eight patients in a persistent vegetative state was measured and compared with that in five healthy volunteers. The patients were classified into three groups: Group 1 (locked-in syndrome) consisted of a single patient, Group 2 (typical vegetative state) of five patients, and Group 3 (prolonged coma) of two patients. CBF was measured early after onset by single photon emission computed tomography with 123I-N-isopropyl-p-iodo-amphetamine and/or 99mTc-hexamethyl-propyleneamine oxime. The regions of interest (ROIs) were the bilateral frontal, temporal, parietal, occipital, and cerebellar areas and basal ganglia. The values obtained in these areas were averaged, and the ratio for each ROI [(the value in the ROI/the mean value) x 100] was calculated. "Hyperfrontal distribution" of CBF was found to be rare in both the normal condition and the vegetative state. Higher CBF values were noted in the left than in the right frontal area in four of the five volunteers but in only four of the eight patients. CBF distribution in the frontal lobe was characteristic for each group: Group 1 showed high CBF bilaterally, although the elevation was statistically significant only on the right side, and Group 3 exhibited significantly low values. In Group 2, CBF was variable but, for the most part, within normal limits. Awareness was closely correlated with frontal lobe function and alteration of CBF in the frontal region.  相似文献   
78.
Clarithromycin (TE-031, A-56268), a new macrolide antibiotic agent, was evaluated bacteriologically and clinically for its efficacy and safety in pediatrics by a study group organized with pediatricians from all over the country. A summary of the results of the evaluation is as follows. 1. Absorption and excretion Pharmacokinetics of TE-031 was examined by single oral administration of 10% granules and 50 mg tablets at doses of 1, 5, 10 and 15 mg/kg. There were no significant differences between 10% granules and 50 mg tablets, and between administrations before and after meal. Peaks and half-life periods of blood level of TE-031 given once at doses of 5, 10 and 15 mg/kg (10% granules) before meal were 1.58, 4.37 and 3.79 micrograms/ml, and 2.53, 3.17 and 2.20 hours, respectively, and the urinary excretion in 6 hours after the administration were about 20-30%. 2. Antibacterial effects TE-031 was proved to have excellent antibacterial effect, i.e., inhibiting growth over 80% of strains of Streptococcus pneumoniae and Streptococcus pyogenes at 0.10 micrograms/ml, Branhamella catarrhalis at 0.39 micrograms/ml, and Campylobacter jejuni at 0.78 micrograms/ml. Against Staphylococcus aureus, TE-031 showed very similar activity spectrum to EM, and EM resistant strains were also resistant to TE-031. 3. Clinical results A total of 764 cases was studied. Clinical effects of TE-031 were evaluated in 717 cases out of the 764, excluding drop-outs and cases which did not meet specified protocols. Clinically, efficacies of TE-031 were "excellent" in 265 cases and "good" in 161 cases out of 453 cases of Group A in which causal agents were identified, with an efficacy rate of 94.0%, and out of 264 cases of Group B in which pathogens were not detected, clinical effects of TE-031 were "excellent" in 115 cases and "good" in 124 cases, with an efficacy rate of 90.5%. In terms of clinical effects of TE-031 classified by diseases when Group A and B were combined, efficacy rates were 91.6% for upper respiratory tract infection (217/237), 90.0% for bacterial pneumonia (108/120), 97.4% for Mycoplasma pneumonia (111/114), 100% for Chlamydia pneumonia (4/4), 85.0% for pertussis (34/40), 100% for scarlet fever (16/16), 83.9% for skin and soft tissue infection (26/31), and 98.9% for Campylobacter enteritis (87/88).(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
79.
Patients with acute (2,569) and chronic (957) leukemia diagnosedat 19 institutes took part in the study on the "MultidisciplinaryTreatment of Leukemia" between 1971 and 1985 and were investigatedretrospectively. By dividing the 15 years into three five-yearperiods, we were able to compare patient ratios in the differentperiods. The proportions of acute to chronic leukemia casesshowed no obvious change; however, the proportions of casesdiagnosed as acute lymphocytic leukemia in acute leukemia showeda significant increase. The main chemotherapeutic drugs usedduring the three time periods were cytarabine or its analogues,the anthracyclines, 6-mercaputopurine and prednisolone, againstacute myelogenous leukemia, and the vinca alkaloids, prednisoloneand the anthracyclines against acute lymphocytic leukemia. Therate of complete remission from acute myelogenous leukemia mademarked progress, from 45.1% during 1971–1975 to 62.3%during 1981–1985, but that of acute lymphocytic leukemiashowed no significant progress, being 65% during 1971–1975and 69.7% during 1981–1985. The durations of remission,however, and the survival times for patients with acute lymphocyticleukemia, as well as for those with acute myelogenous leukemia,became significantly longer over the three periods. Median survivaltimes from chronic myelocytic leukemia were 37–40 mo inall three periods, showing no progress. There was a better prognosisin cases of chronic myelocytic leukemia with, than without,Philadelphia chromosome. Except for a low incidence of chroniclymphocytic leukemia in Japan, adult leukemia patients' characteristicsand prognoses seem to be almost the same in Japan as in theU.S.A. and Europe.  相似文献   
80.
The interaction between polymer and solvent in highly concentrated polymer solutions was studied by inverse gas-liquid chromatography as a function of the molecular weight of polymer. The heat interaction parameter was estimated for the systems polystyrene(PS)-benzene, -toluene, -pyridine, -ethylbenzene, and -anisole. It was found that the heat interaction parameter for the concentrated polystyrene systems PS-toluene, PS-pyridine, and PS-benzene exhibits a similar behavior as in the dilute polystyrene solutions determined by calorimetry at 298,15 K. Further, the heat interaction parameter in both the concentrated and dilute polymer solutions is considerably dependent on the molecular weight of polymer.  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