全文获取类型
收费全文 | 21180篇 |
免费 | 1496篇 |
国内免费 | 72篇 |
专业分类
耳鼻咽喉 | 304篇 |
儿科学 | 654篇 |
妇产科学 | 475篇 |
基础医学 | 3168篇 |
口腔科学 | 561篇 |
临床医学 | 2201篇 |
内科学 | 4253篇 |
皮肤病学 | 328篇 |
神经病学 | 1921篇 |
特种医学 | 955篇 |
外国民族医学 | 1篇 |
外科学 | 2817篇 |
综合类 | 224篇 |
一般理论 | 50篇 |
预防医学 | 1684篇 |
眼科学 | 453篇 |
药学 | 1572篇 |
中国医学 | 23篇 |
肿瘤学 | 1104篇 |
出版年
2022年 | 93篇 |
2021年 | 299篇 |
2020年 | 177篇 |
2019年 | 311篇 |
2018年 | 375篇 |
2017年 | 318篇 |
2016年 | 347篇 |
2015年 | 360篇 |
2014年 | 476篇 |
2013年 | 933篇 |
2012年 | 1104篇 |
2011年 | 1244篇 |
2010年 | 711篇 |
2009年 | 611篇 |
2008年 | 1144篇 |
2007年 | 1185篇 |
2006年 | 1093篇 |
2005年 | 1105篇 |
2004年 | 1148篇 |
2003年 | 1075篇 |
2002年 | 1070篇 |
2001年 | 361篇 |
2000年 | 294篇 |
1999年 | 348篇 |
1998年 | 306篇 |
1997年 | 253篇 |
1996年 | 241篇 |
1995年 | 211篇 |
1994年 | 202篇 |
1993年 | 193篇 |
1992年 | 232篇 |
1991年 | 213篇 |
1990年 | 202篇 |
1989年 | 244篇 |
1988年 | 206篇 |
1987年 | 210篇 |
1986年 | 189篇 |
1985年 | 170篇 |
1984年 | 186篇 |
1983年 | 143篇 |
1982年 | 196篇 |
1981年 | 163篇 |
1980年 | 159篇 |
1979年 | 126篇 |
1978年 | 118篇 |
1977年 | 108篇 |
1976年 | 95篇 |
1975年 | 77篇 |
1974年 | 90篇 |
1973年 | 82篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
41.
Gunter Deppe M.D. Marc L. Kahn M.D. Vinay K. Malviya M.D. John M. Malone Jr. M.D. Carl W. Christensen M.D. Ph.D. 《Gynecologic oncology》1996,62(3):340-343
Experience with the P.A.S.-PORT, a peripherally implanted central venous access device, is evaluated in a retrospective review of 154 patients from July 1991 to June 1994. Blood could not be aspirated from six patients. Complications included temporary minor thrombophlebitis in seven patients (4.5%), symptomatic axillary or subclavian vein thrombosis in five patients (3.2%), clotted port in two patients (1.2%), port pocket cellulitis in two patients (1.2%), and fungal sepsis in two patients (1.2%). In six patients (3.8%) the P.A.S.-PORT had to be removed because of complications. The P.A.S.-PORT facilitated delivery of chemotherapy, parenteral nutrition, blood products, antibiotics, hydration, and blood sampling. It was demonstrated that the P.A.S.-PORT may be inserted and used with a low incidence of complications in gynecologic cancer patients. 相似文献
42.
43.
C Bohm T Greitz R Seitz L Eriksson 《Journal of cerebral blood flow and metabolism》1991,11(2):A64-A68
The computerized individually adjustable brain atlas (CBA) has been further developed. The atlas was primarily designed for anatomical localization and quantitative evaluation of data in positron emission tomography (PET), but may also be employed for other neuroimaging modalities, such as transmission computed tomography (CT) and magnetic resonance imaging (MRI). The atlas is based on anatomical information obtained from digitized cryosectioned brains. Using spatially standardized and then averaged MRI images, we demonstrate the high localization accuracy and precision of the brain atlas. This is a prerequisite for obtaining accuracy when using the atlas in the localization and the quantitative evaluation of PET data. The specification and the selection of region of interests (ROIs) by the CBA are presented and discussed. 相似文献
44.
45.
Ohne Zusammenfassung 相似文献
46.
André H. Eriksson Manthena V.S. Varma Everett J. Perkins Cheryl L. Zimmerman 《Journal of pharmaceutical sciences》2010,99(3):1574-1581
LY354740 is a potent mGlu2/3 agonist with a limited oral bioavailability. Its alanyl prodrug, LY544344, showed high affinity to the intestinal peptide transporter PEPT1, and improved the oral bioavailability of LY354740 in various animal models. The aim of the present study was to investigate the mechanism of in vivo absorption of the dipeptidic prodrug LY544344. The permeabilities of LY544344 and LY354740 were examined in the rat in situ single‐pass intestinal perfusion model. The intestinal absorptive flux of LY354740 was shown to be very low in comparison with LY544344. The absorptive flux of LY544344 could best be described by a Michaelis–Menten process in parallel with a linear process. The estimated parameters were: Jmax = 26.7 × 10?5 µmol/(cm2‐s), Km = 2.6 mM. The absorptive permeability of LY544344 was reduced to approximately 5% of control in the presence of excess Gly‐Sar, a known PEPT1 substrate. Intracellular accumulation of LY354740 and LY544344, estimated postperfusion, showed high levels of LY354740 over LY544344 at all perfusate concentrations studied. However, there was a decline in the intracellular ratio of LY354740 to LY544344 at higher concentrations, suggesting that the metabolic activation to release LY354740 is saturable. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1574–1581, 2010 相似文献
47.
Chymases (EC 3.4.21.39) are mast cell serine proteinases that are variably expressed in different species and, in most cases, display either chymotryptic or elastolytic substrate specificity. Given that chymase inhibitors have emerged as potential therapeutic agents for treating various inflammatory, allergic, and cardiovascular disorders, it is important to understand interspecies differences of the enzymes as well as the behavior of inhibitors with them. We have expressed chymases from humans, macaques, dogs, sheep (MCP2 and MCP3), guinea pigs, and hamsters (HAM1 and HAM2) in baculovirus-infected insect cells. The enzymes were purified and characterized with kinetic constants by using chromogenic substrates. We evaluated in vitro the potency of five nonpeptide inhibitors, originally targeted against human chymase. The inhibitors exhibited remarkable cross-species variation of sensitivity, with the greatest potency observed against human and macaque chymases, with Ki values ranging from ∼0.4 to 72 nM. Compounds were 10-300-fold less potent, and in some instances ineffective, against chymases from the other species. The X-ray structure of one of the potent phosphinate inhibitors, JNJ-18054478, complexed with human chymase was solved at 1.8 Å resolution to further understand the binding mode. Subtle variations in the residues in the active site that are already known to influence chymase substrate specificity can also strongly affect the compound potency. The results are discussed in the context of selecting a suitable animal model to study compounds ultimately targeted for human chymase. 相似文献
48.
Liesbeth Vandenput Fernand Labrie Dan Mellstr?m Charlotte Swanson Thomas Knutsson Ralph Peeker Osten Ljunggren Eric Orwoll Anna L Eriksson Jan-Erik Damber Claes Ohlsson 《Journal of bone and mineral research》2007,22(2):220-227
Androgens are important regulators of bone and prostate health in elderly men. The role of serum levels of glucuronidated androgen metabolites as predictors of BMD and prostate volume in men is unclear. We show that specific glucuronidated androgen metabolites predict BMD and prostate volume in elderly men. INTRODUCTION: Androgens are important regulators of bone and prostate health in elderly men. Local synthesis and degradation of androgens are likely to be important parameters of biological action of androgens in androgen-responsive tissues. The aim of this study was to determine the role of serum levels of glucuronidated androgen metabolites as predictors of BMD and prostate volume in elderly men. MATERIALS AND METHODS: A subsample of the population-based Swedish part of the MrOS study (n = 631, average age = 75.9 years) was investigated. Bone parameters were measured using DXA. Serum levels of total testosterone (T) and dihydrotestosterone (DHT) were measured by gas chromatography/mass spectroscopy (GC-MS); androstane-3alpha,17beta-diol-3glucuronide (3G) and androstane-3alpha,17beta-diol-17glucuronide (17G) were measured by liquid chromatography/mass spectroscopy. Prostate volume (n = 159) was measured by transrectal ultrasound. RESULTS: The general pattern is that two of the glucuronidated androgen metabolites, namely 17G and 3G, are stronger positive predictors of BMD than the bioactive androgens (T and DHT). In addition, 17G is a clear positive predictor of prostate volume, explaining 4.5% of the variance in prostate volume, whereas the bioactive androgens do not display any association with prostate volume. CONCLUSIONS: Serum levels of specific glucuronidated androgen metabolites predict BMD and prostate volume in elderly men. Future studies should determine if the glucuronidated androgen metabolites also reflect other biological correlates of androgenic activity, including prostate cancer, and if low levels might be a marker of general androgen deficiency in men. 相似文献
49.
50.
Carl E Bartecchi 《Journal of the American College of Cardiology》2006,47(7):1498-9; author reply 1499-500