全文获取类型
收费全文 | 7030篇 |
免费 | 419篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 79篇 |
儿科学 | 249篇 |
妇产科学 | 80篇 |
基础医学 | 1215篇 |
口腔科学 | 107篇 |
临床医学 | 528篇 |
内科学 | 1654篇 |
皮肤病学 | 188篇 |
神经病学 | 743篇 |
特种医学 | 256篇 |
外科学 | 587篇 |
综合类 | 50篇 |
预防医学 | 388篇 |
眼科学 | 160篇 |
药学 | 557篇 |
中国医学 | 12篇 |
肿瘤学 | 634篇 |
出版年
2024年 | 4篇 |
2023年 | 72篇 |
2022年 | 119篇 |
2021年 | 162篇 |
2020年 | 93篇 |
2019年 | 145篇 |
2018年 | 182篇 |
2017年 | 147篇 |
2016年 | 150篇 |
2015年 | 129篇 |
2014年 | 224篇 |
2013年 | 304篇 |
2012年 | 479篇 |
2011年 | 476篇 |
2010年 | 273篇 |
2009年 | 299篇 |
2008年 | 456篇 |
2007年 | 529篇 |
2006年 | 469篇 |
2005年 | 500篇 |
2004年 | 501篇 |
2003年 | 463篇 |
2002年 | 472篇 |
2001年 | 60篇 |
2000年 | 38篇 |
1999年 | 61篇 |
1998年 | 89篇 |
1997年 | 80篇 |
1996年 | 69篇 |
1995年 | 62篇 |
1994年 | 39篇 |
1993年 | 61篇 |
1992年 | 49篇 |
1991年 | 36篇 |
1990年 | 29篇 |
1989年 | 23篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 7篇 |
1980年 | 13篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1973年 | 5篇 |
排序方式: 共有7487条查询结果,搜索用时 15 毫秒
971.
Orlando Campos Jose L. Andrade Jose Bocanegra John A. Ambrose Antonio C. Carvalho Keiko Harada Eulogio E. Martinez 《International journal of cardiology》1993,40(3):265-272
Valvular function, assessed by Doppler technique, has not been extensively investigated during normal pregnancy. To prospectively study this feature, 18 normal pregnant women were followed during their pregnancies and puerperium, with serial clinical and pulsed-continuous Doppler echocardiographic examinations. In four gestational periods and the puerperium, we analysed: (a) ventricular and atrial dimensions, as well as valve annular diameters; (b) prevalence and characteristics of trivial valvular regurgitations. During pregnancy, slight but significant increases of the four cardiac chamber dimensions and valve annular diameters were observed, except for the aortic ring. The prevalence of physiologic valvular regurgitation in early pregnancy (mitral, 0%; tricuspid, 38.9%; pulmonary, 22.2%; aortic, 0%), was similar to a control group of 18 healthy non-pregnant women. As pregnancy evolved, there was a progressive and significant increase of multivalvular regurgitation, maximal at full-term (mitral, 27.8%; tricuspid, 94.4%; pulmonary, 94.4%, P < 0.05 vs. early pregnancy). Aortic regurgitation was not detected in any stage of pregnancy. In the puerperium, mitral regurgitation resolved, but tricuspid and pulmonary regurgitation were still significantly prevalent (83.3% and 66.7%, respectively, P < 0.05 vs. early pregnancy). It is concluded that physiologic multivalvular regurgitation is frequent in pregnancy, mainly involving right-sided valves in late gestational periods, occasionally persisting in the early puerperium. Chamber enlargement, valve annular dilatation, and increased prevalence of trivial valve regurgitation are time-related events during normal pregnancy, resulting from a reversible cardiac remodeling process induced by physiologic volume overload. These aspects should be considered for a correct interpretation of Doppler echocardiographic findings in pregnant women with suspected heart disease. 相似文献
972.
973.
Male Wistar-MS (W&MS), Fisher-344 (F-344) and SpragueDkawley(SD) rats were divided into four groups including a controlgroup implanted with a cholesterol pellet. Rats in the threeexperimental groups were treated with 相似文献
974.
Yoshihiro KOHLI Takuji KATO Shigeji ITO Hideo MIYAZI Takeshi AZUMA Kumiko NAGATA Hitoshi TSURUTA Satomi MATSUI Keiko OKA Michihiro NAKAMURA 《Digestive endoscopy》1995,7(1):27-34
A rapid diagnostic system for Helicobacter pylori (H. pylori) was developed based on an urease analyser using a pH-sensitive field effect transistor (pH-FET). The system is composed of a solid-phase capillary-tube and a pH-measuring cell. The solid-phase tube, with an inner diameter 0.55 mm and coated with a monoclonal antibody against H. pylori's urease, was used to selectively capture the urease in endoscopically collected gastric mucus. The urease activity on the inner surface of the solid-phase tube was measured by coupling it with ph-FET in a pH measuring cell containing urea solution. Before immuno reaction in the solid-phase, gastric mucus was diluted with a phosphate buffered saline containing 1% n-octylglucoside, which was effective for accelerating the release of active urease from H. pylori's cells suspended in the sample solution. As a result of preliminary evaluations, it was found that the clinical sensitivity and specificity were 100 and 86%, respectively, using a bacteriological test as a reference. 相似文献
975.
Keiko Muguruma Kazuyuki Imamura Hiroshi Morii Yasuyoshi Watanabe 《Brain research》1996,740(1-2):131-140
To examine how adrenergic receptor binding is modified by experimental manipulation of sensory afferent, we carried out binding experiments (membrane fraction and in vitro autoradiography) for both 2- and β-adrenergic receptors in the brain of cats which had been deprived of vision in one eye. In the cerebral cortex of control animals, β-adrenergic receptor (β-AR) binding was found to be higher in the occipital regions than in other regions, while 2-AR binding was relatively uniform. Monocular deprivation throughout the postnatal sensitive period (1–7 month of age) significantly decreased β-AR binding in the visual cortex and lateral geniculate nucleus. Scatchard plot analysis in the visual cortex showed ca. 50% reduction in Bmax and little change in Kd No significant difference was found in 2-AR binding following monocular deprivation. Similar extent of down-regulation in β-AR binding was confirmed in all layers of visual cortex using autoradiography. 相似文献
976.
Comparative dose-response study on the pulmonary carcinogenicity of 1, 6-dinitropyrene and benzo[a]pyrene in F344 rats 总被引:1,自引:0,他引:1
Iwagawa Masanori; Maeda Toshiharu; Izumi Keisuke; Otsuka Hisashi; Nishifuji Keiko; Ohnishi Yoshinari; Aoki Shigenobu 《Carcinogenesis》1989,10(7):1285-1290
The dose dependencies of the lung carcinogenicity of 1, 6-dinitropyrene(1, 6-DNP) and benzo[a]pyrene (BaP) were examined by directinjections of these compounds into rat lungs. A total of 276male F344 rats were divided into 10 groups and given variousdoses of 1, 6-DNP or BaP, or no drug (control group). Both chemicalswere injected into the lung, as suspensions in beeswax-tricaprylinand the animals were then observed for 104 weeks. The incidencesof lung cancer were 0/39 (0%), 4/30 (13%), 13/31 (42%), 22/26(85%) and 6/9 (67%) in groups treated with 0.003, 0.01, 0.03,0.1 and 0.15 mg of 1, 6-DNP respectively, and 1/29 (3%), 7/30(23%) 22/29 (76%) and 9/13 (69%) in those treated with 0.03,0.1, 0.3 and 1.0 mg of BaP respectively. No lung cancer wasfound in control rats. Thus the incidences of lung cancer inducedby 1, 6-DNP and BaP showed significant dose dependence. At equaldoses, the incidence of lung cancer was much higher with 1,6-DNP than with BaP, and the induction of cancer by 1, 6-DNPwas higher even at one-third the dose of BaP. Histologically,most tumours induced by 1, 6-DNP were undifferentiated neoplasms,whereas most of those induced by BaP were well-differentiatedsquamous cell carcinomas. 相似文献
977.
Wistar rats were implanted with a probe for brain microdialysis in the striatum, and measured for two major dopamine metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). Intraperitoneal chlorpromazine (5 mg/kg) increased the concentrations of both metabolites in the dialysate when the determinations were carried out before 90 min after the administration. An apparent difference between the declines in concentrations of DOPAC and HVA was observed. Although the concentration of HVA maintained higher levels for over 6 h after the administration, DOPAC underwent a decrease in its concentration after the maximum level, which occurred at 90 min after the administration. These results are discussed in terms of the different distributions of two enzymes related to the metabolism of dopamine, catechol-O-methyltransferase and monoamine oxidase. 相似文献
978.
Masafumi Harada Hiromu Nishitani Keiko Koga Iwao Miura Yukihiko Umeno 《Cancer science》1992,83(4):387-391
Metabolism of tegafur in the rat liver was observed by in-vivo 19 F magnetic resonance spectroscopy (MRS). After MRS observation, tegafur and q-fluorouracil (S-FU) in the liver were determined by a shromatographic method for comparison with the results of 19 F-MRS. Rats were divided into 3 groups: 1) CCl4-induced liver injury group, 2) uracil combined group, 3) control group. Catabolism to fluoro-β-alanine was suppressed in both the liver injury group and the uracil combined group. Low peaks of 5-FU and fluoronucleotides could be found only in the uracil combined group. The result of 19 F MRS observation of each group was in agreement with the result of determination of tegafur and 5-FU by chromatography. This showed that substances which could be observed by 19 F-MRS were in proportion to all intracelluar fluoro-containing substances. 19 F-MRS can provide direct information on the metabolism of fluoropyimidines non-invasivey and it might be a useful aid in choosing suitable shemotherapy for patients. 相似文献
979.
Keiko Ariyoshi Hirofumi Hamada Mikihiko Naito Yuji Heike Hiroyuki Seimiya Kayoko Maezawa Takashi Tsuruo 《Cancer science》1992,83(5):515-521
We have developed a mouse-human chimeric antibody MH171, in which the antigen-recognizing variable regions of the mouse monoclonal antibody MRK17 are joined with the constant regions of human IgG1 antibodies. The MRK17 recognizes specifically the multidrug transporter P-glycoprotein and inhibits the growth of human multidrug resistant (MDR) tumor cells in vitro and in the xenograft nude mouse model system. The established chimeric MH171 antibody forms an apparently intact IgG composed of heavy and light chains covalently assembled via disulfide bonds in sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis and is specific to MDR cell lines with a similar affinity to the original mouse MRK17. MH171 also displays strong antibody-dependent cell-mediated cytotoxicity to the target cells in vitro , when human mononuclear cells are used as effector cells. The chimeric antibody against P-glycoprotein, MH171, should be a useful agent in the treatment of human drug-resistant tumors. 相似文献
980.
We investigated trends in neurological complications of infection with human immunodeficiency virus (HIV) in Japan after the introduction of highly active antiretroviral therapy (HAART). Two questionnaire surveys were performed in hospitals treating acquired immunodeficiency syndrome (AIDS) to compare two periods: immediately after the introduction of HAART (1999-2001); and a few years later (2002-3). Neurological complications accompanied 15.9% in 1999-2001 and 9.8% in 2002-3. Neurological complications developed without HAART in about 80% of cases. Neurological complications developed as the first AIDS-defining disease for 8.3% of AIDS patients in 1999-2001 and for 5.4% in 2002-3. Prevalences of HIV encephalopathy and myelopathy decreased markedly over the study period, as reported in other developed nations. However, prevalences of cytomegalovirus encephalitis, PML and primary brain lymphoma did not decrease. PML and primary brain lymphoma occurred in patients who received HAART and whose CD4 counts were relatively high during the study period. This is probably related to the extended survival of HIV-infected individuals after the introduction of HAART as a worldwide therapy, and the reactivation of viremia or latent infection persisting within the central nervous system. 相似文献