全文获取类型
收费全文 | 93892篇 |
免费 | 8374篇 |
国内免费 | 212篇 |
专业分类
耳鼻咽喉 | 1030篇 |
儿科学 | 2824篇 |
妇产科学 | 2334篇 |
基础医学 | 12768篇 |
口腔科学 | 1989篇 |
临床医学 | 10977篇 |
内科学 | 18586篇 |
皮肤病学 | 1383篇 |
神经病学 | 8471篇 |
特种医学 | 3001篇 |
外国民族医学 | 1篇 |
外科学 | 13580篇 |
综合类 | 1865篇 |
一般理论 | 97篇 |
预防医学 | 8847篇 |
眼科学 | 1871篇 |
药学 | 7184篇 |
1篇 | |
中国医学 | 111篇 |
肿瘤学 | 5558篇 |
出版年
2022年 | 605篇 |
2021年 | 1342篇 |
2020年 | 867篇 |
2019年 | 1456篇 |
2018年 | 1729篇 |
2017年 | 1304篇 |
2016年 | 1441篇 |
2015年 | 1691篇 |
2014年 | 2393篇 |
2013年 | 3680篇 |
2012年 | 5259篇 |
2011年 | 5550篇 |
2010年 | 3169篇 |
2009年 | 2900篇 |
2008年 | 5155篇 |
2007年 | 5482篇 |
2006年 | 5354篇 |
2005年 | 5376篇 |
2004年 | 5186篇 |
2003年 | 4790篇 |
2002年 | 4857篇 |
2001年 | 2013篇 |
2000年 | 1855篇 |
1999年 | 1850篇 |
1998年 | 1324篇 |
1997年 | 1079篇 |
1996年 | 933篇 |
1995年 | 902篇 |
1994年 | 818篇 |
1993年 | 772篇 |
1992年 | 1407篇 |
1991年 | 1305篇 |
1990年 | 1261篇 |
1989年 | 1185篇 |
1988年 | 1093篇 |
1987年 | 1074篇 |
1986年 | 1091篇 |
1985年 | 1115篇 |
1984年 | 1035篇 |
1983年 | 900篇 |
1982年 | 812篇 |
1981年 | 694篇 |
1980年 | 694篇 |
1979年 | 756篇 |
1978年 | 627篇 |
1977年 | 538篇 |
1976年 | 537篇 |
1974年 | 522篇 |
1973年 | 466篇 |
1972年 | 423篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Guo-Lin Wei Juri Melnik Jing-Li Luo Alan R. Sanger Karl T. Chuang 《Journal of electroanalytical chemistry (Lausanne, Switzerland)》2005,575(2):183-193
The performances of three widely different cathode materials (Pt, strontium-doped lanthanum manganite (LSM), and NiO) have been compared for use with proton conducting Li2SO4–Al2O3 composite electrolyte, using H2S–air and H2–air fuel cells operating at 600 °C. Surface analysis and electrochemical techniques were used to characterize fresh and used electrode materials. Pt or LSM cathodes each became covered with Li2SO4 and Al2O3 and, as a consequence, the fuel cells showed poor performance. In contrast, the NiO cathode catalyst did not become covered with Li2SO4 and good fuel cell performance was achieved. Exceptionally good current densities of over 100 mA/cm2 and power densities of over 30 mW/cm2 were obtained for H2S–air fuel cells having Mo–Ni–S anode catalysts. Slight agglomeration of NiO particles during fuel cell operation had only a minor effect on performance. 相似文献
73.
Phospho-akt expression is associated with a favorable outcome in non-small cell lung cancer. 总被引:3,自引:0,他引:3
Amit Shah William A Swain Donna Richardson John Edwards Duncan J Stewart Catherine M Richardson Daniel E B Swinson Dipika Patel J Louise Jones Kenneth J O'Byrne 《Clinical cancer research》2005,11(8):2930-2936
Akt, a Serine/Threonine protein kinase, mediates growth factor-associated cell survival. Constitutive activation of Akt (phosphorylated Akt, P-Akt) has been observed in several human cancers, including lung cancer and may be associated with poor prognosis and chemotherapy and radiotherapy resistance. The clinical relevance of P-Akt in non-small cell lung cancer (NSCLC) is not well described. In the present study, we examined 82 surgically resected snap-frozen and paraffin-embedded stage I to IIIA NSCLC samples for P-Akt and Akt by Western blotting and for P-Akt by immunohistochemistry. P-Akt protein levels above the median, measured using reproducible semiquantitative band densitometry, correlated with a favorable outcome (P = 0.007). Multivariate analysis identified P-Akt as a significant independent favorable prognostic factor (P = 0.004). Although associated with a favorable prognosis, high P-Akt levels correlated with high tumor grade (P = 0.02). Adenocarcinomas were associated with low P-Akt levels (P = 0.039). Akt was not associated with either outcome or clinicopathologic variables.Cytoplasmic (CP-Akt) and nuclear (NP-Akt) P-Akt tumor cell staining was detected in 96% and 42% of cases, respectively. Both CP-Akt and NP-Akt correlated with well-differentiated tumors (P = 0.008 and 0.017, respectively). NP-Akt also correlated with nodal metastases (P = 0.022) and squamous histology (P = 0.037).These results suggest P-Akt expression is a favorable prognostic factor in NSCLC. Immunolocalization of P-Akt, however, may be relevant as NP-Akt was associated with nodal metastases, a known poor prognostic feature in this disease. P-Akt may be a potential novel therapeutic target for the management of NSCLC. 相似文献
74.
75.
76.
77.
C. T. Laurencin R. S. Cummings T. R. Jones L. Martin 《Journal of the National Medical Association》1998,90(12):779-781
Bony fusions involving the carpus have a much higher prevalence in blacks relative to whites. This article describes a case of lunotriquetral coalition fracture-dislocation in an African American. This lesion is best treated through open reduction and pin fixation. 相似文献
78.
David W. Farley DDS John D. Jones DDS Robert J. Cronin DDS MS 《Journal of prosthodontics》1998,7(2):84-90
Phonetics, esthetics, function, and comfort form the foundation of a successful dental prosthesis. A review of the mechanics of speech as well as common speech problems encountered with a removable maxillary prosthesis are presented. The use of a palatogram to aid the clinician in the assessment and resolution of speech problems associated with a maxillary denture is demonstrated. 相似文献
79.
A P Jones A Sofat C H Davis S Denton N T Gurusinghe 《British journal of neurosurgery》1990,4(3):193-197
The high cost of commercial CT-compatible stereotactic frames has restricted the availability of CT-guided stereotaxy for many neurosurgical centres. However, many of these centres do possess the standard stereotactic frames for projection radiography, of which the old type Leksell frame is probably the most common. We have devised a simple and low-cost modification to an old Leksell frame to allow CT-guided stereotaxy. The nature of the modifications allow complete freedom of positioning of the frame relative to the CT scanner and coordinate transformations can be performed simply and effectively. The modified frame has been used successfully for some 18 months and the modification has now been performed at two centres in the North West Regional Health Authority. We hope this modification will allow many other centres to embark on CT-guided stereotaxy. 相似文献
80.
Immunoassay procedures, both enzyme immunoassay and radioimmunoassay, continue to be widely used to screen samples for recent marijuana use by analyzing the urine samples for 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (11-nor-delta 9-THC-9-COOH) (the major urinary metabolite of delta 9-tetrahydrocannabinol [delta 9-THC]). Using commercially available immunoassay reagents, the cross-reactivity of the antiserum utilized in Abbott's TDx cannabinoid assay (a fluorescence polarization immunoassay) was evaluated. This cross-reactivity was evaluated against a group of cannabinoids and noncannabinoid phenolic constituents of Cannabis, some cannabinoid metabolites, and other agents that appear in normal urine samples. In general, the antiserum was equally reactive toward 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid, its glucuronide, and the corresponding delta 8-isomer, which was the acid moiety utilized in standards and controls of the assay prior to January, 1990. Reduced binding to the antiserum was observed with hydroxylated derivatives of delta 9- and delta 8-THC, and the other cannabinoids, in general, exhibited limited binding potentials toward the antibody. For the noncannabinoid constituents, no binding was observed at the highest concentrations evaluated (40 mg/L). 相似文献