全文获取类型
收费全文 | 4289篇 |
免费 | 402篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 41篇 |
儿科学 | 122篇 |
妇产科学 | 108篇 |
基础医学 | 519篇 |
口腔科学 | 88篇 |
临床医学 | 497篇 |
内科学 | 1007篇 |
皮肤病学 | 35篇 |
神经病学 | 326篇 |
特种医学 | 181篇 |
外科学 | 363篇 |
综合类 | 174篇 |
一般理论 | 8篇 |
预防医学 | 499篇 |
眼科学 | 40篇 |
药学 | 381篇 |
中国医学 | 8篇 |
肿瘤学 | 314篇 |
出版年
2021年 | 70篇 |
2020年 | 49篇 |
2019年 | 66篇 |
2018年 | 77篇 |
2017年 | 43篇 |
2016年 | 50篇 |
2015年 | 68篇 |
2014年 | 95篇 |
2013年 | 146篇 |
2012年 | 178篇 |
2011年 | 227篇 |
2010年 | 94篇 |
2009年 | 105篇 |
2008年 | 176篇 |
2007年 | 225篇 |
2006年 | 202篇 |
2005年 | 212篇 |
2004年 | 198篇 |
2003年 | 173篇 |
2002年 | 207篇 |
2001年 | 153篇 |
2000年 | 144篇 |
1999年 | 132篇 |
1998年 | 59篇 |
1997年 | 64篇 |
1996年 | 56篇 |
1995年 | 63篇 |
1994年 | 41篇 |
1993年 | 30篇 |
1992年 | 71篇 |
1991年 | 92篇 |
1990年 | 64篇 |
1989年 | 97篇 |
1988年 | 93篇 |
1987年 | 97篇 |
1986年 | 61篇 |
1985年 | 71篇 |
1984年 | 51篇 |
1983年 | 35篇 |
1982年 | 33篇 |
1979年 | 44篇 |
1978年 | 26篇 |
1977年 | 26篇 |
1975年 | 30篇 |
1974年 | 29篇 |
1973年 | 41篇 |
1972年 | 30篇 |
1971年 | 29篇 |
1970年 | 27篇 |
1969年 | 27篇 |
排序方式: 共有4711条查询结果,搜索用时 15 毫秒
61.
Phase I trial and pharmacokinetic study of BMS-247550, an epothilone B analog, administered intravenously on a daily schedule for five days. 总被引:4,自引:0,他引:4
Jame Abraham Manish Agrawal Susan Bakke Ann Rutt Maureen Edgerly Frank M Balis Brigitte Widemann Louis Davis Bharat Damle Daryl Sonnichsen David Lebwohl Susan Bates Herb Kotz Tito Fojo 《Journal of clinical oncology》2003,21(9):1866-1873
PURPOSE: The epothilones are a novel class of nontaxane microtubule-stabilizing agents. BMS-247550 is a semisynthetic analog of the natural product epothilone B. We conducted a phase I study administering BMS-247550 as a 1-hour intravenous infusion daily for 5 consecutive days every 21 days. PATIENTS AND METHODS: Twenty-one patients received BMS-247550 without filgrastim in the first cycle. An additional six patients were enrolled at a starting dose of 8 mg/m2/d with filgrastim support. Twenty-one of the 27 patients had received prior paclitaxel, docetaxel, or both. RESULTS: One hundred seven cycles were administered to 27 patients. The maximum-tolerated dose was 6 mg/m2 of BMS-247550 administered as a 1-hour intravenous infusion daily for 5 consecutive days every 21 days. Dose-limiting toxicity at a dose of 8 mg/m2/d was neutropenia with or without filgrastim support. Nonhematologic grade 3 toxicities included fatigue (seven cycles), stomatitis (two cycles), and anorexia (one cycle). The mean terminal half-life of BMS-247550 was 16.8 +/- 6.0 hours, the volume of distribution at steady-state was 798 +/- 375 L, and the clearance was 712 +/- 247 mL/min. Objective responses were observed in patients with breast, cervical, and basal cell cancer. Reductions in CA-125 levels were noted in patients with ovarian cancer. CONCLUSION: The recommended phase II dose of BMS-247550 on the daily schedule for 5 days is 6 mg/m2/d. Neutropenia was dose limiting, but higher doses were tolerated by a large fraction of patients with filgrastim support. Peripheral neuropathy was mild, even after multiple cycles of therapy, and was not dose limiting. 相似文献
62.
BACKGROUND: Acute renal failure (ARF) requiring dialysis after coronary artery bypass grafting (CABG) occurs in 1 to 5% of patients and is independently associated with postoperative mortality, even after case-mix adjustment. A risk-stratification algorithm that could reliably identify patients at increased risk of ARF could help improve outcomes. METHODS: To assess the validity and generalizability of a previously published preoperative renal risk-stratification algorithm, we analyzed data from the Quality Measurement and Management Initiative (QMMI)1 patient cohort. The QMMI includes all adult patients (N = 9498) who underwent CABG at 1 of 12 academic tertiary care hospitals from August 1993 to October 1995. ARF requiring dialysis was the outcome of interest. Cross-validation of a recursive partitioning algorithm developed from the VA Continuous Improvement in Cardiac Surgery Program (CICSP) was performed on the QMMI. An additive severity score derived from logistic regression was also cross-validated on the QMMI. RESULTS: The CICSP recursive partitioning algorithm discriminated well (ARF vs. no ARF) in QMMI patients, even though the QMMI cohort was more diverse. Rates of ARF were similar among risk subgroups in the CICSP tree, as was the overall ranking of subgroups by risk. Using logistic regression, independent predictors of ARF in the QMMI cohort were similar to those found in the CICSP. The CICSP additive severity score performed well in the QMMI cohort, successfully stratifying patients into low-, medium-, high-, and very high-risk groups. CONCLUSIONS: The CICSP preoperative renal-risk algorithms are valid and generalizable across diverse populations. 相似文献
63.
Abril N; Luque-Romero FL; Prieto-Alamo MJ; Rafferty JA; Margison GP; Pueyo C 《Carcinogenesis》1997,18(10):1883-1888
Here we confirm and extend our previous studies demonstrating that the
mutagenic potency of 1,2-dibromoethane (DBE) and dibromomethane (DBM) is
markedly enhanced (not prevented) in bacteria expressing the O6-
alkylguanine-DNA alkyltransferase (ATase) encoded by the Escherichia coli
ogt gene. We demonstrate that, in close parallel with mutagenesis, the Ogt
ATase sensitizes the bacteria to the lethal effects of these carcinogens,
suggesting that one or more of the potentially mutagenic lesions induced by
DBE and DBM in the presence of Ogt has additional lethal capacity. We
further demonstrate that the sensitization to both lethality and
mutagenesis by DBE and DBM is a property shared by other DNA
alkyltransferases. This objective was accomplished by quantifying the
induction of mutations and lethal events in ogt- ada- E. coli expressing an
exogenous bacterial or mammalian ATase from a multicopy plasmid. Mammalian
recombinant ATases enhanced the lethal and mutagenic actions of DBE and
suppressed the lack of sensitivity of the vector- transformed bacteria to
DBM. In most cases the order of effectiveness of the ATases ranked: murine
> human > Ogt > rat. Further comparisons included the full-length
Ada ATase from E. coli and a truncated Ada version (T-ada) that retains the
O6-methylguanine binding domain of the protein. The full-length Ada ATase
was effective in enhancing the lethality but not the mutagenicity induced
by DBE and DBM. The T-ada ATase provided less sensitization than Ada to
lethality by DBE, but of the three bacterial ATases T-ada yielded the
highest sensitization to mutagenesis by this compound. T-ada and Ada ATases
were in general less effective than the mammalian versions, with the
exception of the rat recombinant ATase. The effectiveness of the different
mammalian and bacterial ATases in promoting the deleterious actions of
dibromoalkanes was compared with the effectiveness of these proteins in
suppressing the lethal and mutagenic effects induced by
N-nitroso-N-methylurea. The ability to sensitize E. coli to the lethal and
mutagenic effects of DBE and DBM seems restricted to DNA alkyltransferase,
since overexpression of thioredoxin (Trx) or glutaredoxin (Grx1) in ogt-
ada- cells showed no effect, in spite of the reported potential of
bioactive dihaloethane- derived species to alkylate Trx.
相似文献
64.
65.
Clinical application of a computerized system for physician order entry with clinical decision support to prevent adverse drug events in long-term care 总被引:1,自引:0,他引:1 下载免费PDF全文
66.
Paige Cummings Nathan D. Schilaty Takashi Nagai Luca Rigamonti Ryo Ueno Nathaniel A. Bates 《International Journal of Sports Physical Therapy》2022,17(7):1236
BackgroundPrevious literature has postulated a relationship between greater hamstring stiffness and a higher risk of sustaining injury. Shear wave elastography (SWE) presents a relatively new means for non-invasive evaluation of soft tissue elasticity pre- and post- injury or intervention.Purpose1. To establish baseline hamstring stiffness measures for young competitive athletes and (2) determine effect of targeted neuromuscular training (TNMT) on shear wave stiffness of the hamstring.Study DesignUn-blinded, prospective, non-randomized, cohort study.MethodsSix-hundred forty-two lower extremities from 321 high school and collegiate basketball athletes (177 F: 139 M) were examined for hamstring stiffness prior to the start of their competitive basketball season. Teams were cluster assigned to either the control or intervention (TNMT) group. Subjects in the control group underwent regular season activities as directed, with no influence from the research team. For the TNMT group, the research team introduced a hamstring targeted dynamic warm-up program as an intervention focused on activating the hamstring musculature.ResultsCollegiate status was significant to hamstring stiffness for both sexes (p ≤ 0.02), but hamstring stiffness did not correlate to age or sex (r2 ≤ 0.08). Intervention was a significant factor to hamstring stiffness when the hip was positioned in extension (p ≤ 0.01), but not in deeper flexion (p = 0.12). This effect was sex-specific as TNMT influenced hamstring stiffness in females (p = 0.03), but not in males (p ≥ 0.13). Control athletes suffered three HAM injuries; TNMT athletes suffered 0 hamstring injuries.ConclusionHigher SWE measurements correlated with increased risk of injury, male sex, and collegiate athletics. TNMT intervention can lessen muscle stiffness which may reduce relate to injury incidence. Intervention effectiveness may be sex specific.Level of EvidenceII 相似文献
67.
68.
Stanley CJ Ellis DH Bates DL Johannsson A 《Journal of pharmaceutical and biomedical analysis》1987,5(8):811-820
The sensitivity of enzyme immunoassays may be enhanced by the use of enzyme-amplification. This technique uses the enzyme label in the immunoassay to provide a trigger substance for a secondary system that can generate a large quantity of coloured product. Two examples of enzyme amplifiers are described, using either a substrate cycle with phosphorylated hexose sugars, or a redox cycle involving the coenzyme NAD+. The redox enzyme-amplifier has a detection limit of less than one attomole for the enzyme label, alkaline phosphatase.
The limited dynamic range of enzyme-amplified immunoassays may be overcome by kinetic analysis of the colour development in the enzyme-amplifier, to add at least a further order of magnitude to the range of directly measured analyte concentrations in the immunoassay. This is illustrated in an enzyme-amplified immunoassay for human thyroid stimulating hormone. Amperometric measurement of the enzyme-amplifier provides a method to extend the dynamic range still further and compares favourably with the performance of a gamma counter, a luminometer or a fluorimeter. 相似文献
69.
Lignin is the second-most available biopolymer in nature. In this work, lignin was employed as the carbon precursor for the one-step synthesis of sulfur-doped nanoporous carbons. Sulfur-doped nanoporous carbons have several applications in scientific and technological sectors. In order to synthesize sulfur-doped nanoporous carbons from lignin, sodium thiosulfate was employed as a sulfurizing agent and potassium hydroxide as the activating agent to create porosity. The resultant carbons were characterized by pore textural properties, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The nanoporous carbons possess BET surface areas of 741–3626 m2/g and a total pore volume of 0.5–1.74 cm3/g. The BET surface area of the carbon was one of the highest that was reported for any carbon-based materials. The sulfur contents of the carbons are 1–12.6 at.%, and the key functionalities include S=C, S-C=O, and SOx. The adsorption isotherms of three gases, CO2, CH4, and N2, were measured at 298 K, with pressure up to 1 bar. In all the carbons, the adsorbed amount was highest for CO2, followed by CH4 and N2. The equilibrium uptake capacity for CO2 was as high as ~11 mmol/g at 298 K and 760 torr, which is likely the highest among all the porous carbon-based materials reported so far. Ideally adsorbed solution theory (IAST) was employed to calculate the selectivity for CO2/N2, CO2/CH4, and CH4/N2, and some of the carbons reported a very high selectivity value. The overall results suggest that these carbons can potentially be used for gas separation purposes. 相似文献