全文获取类型
收费全文 | 1284篇 |
免费 | 10篇 |
专业分类
电工技术 | 4篇 |
综合类 | 2篇 |
化学工业 | 58篇 |
金属工艺 | 5篇 |
机械仪表 | 22篇 |
建筑科学 | 21篇 |
矿业工程 | 1篇 |
能源动力 | 16篇 |
轻工业 | 47篇 |
水利工程 | 2篇 |
石油天然气 | 8篇 |
无线电 | 82篇 |
一般工业技术 | 92篇 |
冶金工业 | 817篇 |
原子能技术 | 4篇 |
自动化技术 | 113篇 |
出版年
2022年 | 7篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 21篇 |
2012年 | 14篇 |
2011年 | 26篇 |
2010年 | 11篇 |
2009年 | 16篇 |
2008年 | 21篇 |
2007年 | 23篇 |
2006年 | 21篇 |
2005年 | 22篇 |
2004年 | 16篇 |
2003年 | 19篇 |
2002年 | 14篇 |
2001年 | 17篇 |
2000年 | 17篇 |
1999年 | 35篇 |
1998年 | 225篇 |
1997年 | 129篇 |
1996年 | 103篇 |
1995年 | 66篇 |
1994年 | 48篇 |
1993年 | 50篇 |
1992年 | 13篇 |
1991年 | 17篇 |
1990年 | 17篇 |
1989年 | 16篇 |
1988年 | 8篇 |
1987年 | 23篇 |
1986年 | 18篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1978年 | 5篇 |
1977年 | 31篇 |
1976年 | 55篇 |
1975年 | 6篇 |
1972年 | 4篇 |
1970年 | 4篇 |
1968年 | 4篇 |
1955年 | 4篇 |
排序方式: 共有1294条查询结果,搜索用时 15 毫秒
991.
992.
BA Pockaj RM Sherry JP Wei JR Yannelli CS Carter SF Leitman JA Carasquillo SM Steinberg SA Rosenberg JC Yang 《Canadian Metallurgical Quarterly》1994,73(6):1731-1737
BACKGROUND: The adoptive transfer of interleukin-2 (IL-2)-cultured tumor infiltrating lymphocytes (TIL) can cause tumor regression in patients with metastatic melanoma. METHODS: Thirty-eight patients with metastatic melanoma receiving high dose IL-2 and TIL were studied for the ability of autologous 111In-labeled TIL to localize to metastatic tumor deposits by gamma camera imaging and biopsy. Single bolus cyclophosphamide was administered 24-36 hours before TIL infusion in 27 treatment courses. RESULTS: Tumor localization by 111In-labeled TIL was seen by gamma camera imaging in 26 (68.4%) treatment courses. In a univariate analysis of factors influencing TIL traffic, cyclophosphamide administration was significantly associated with the ability to localize tumor by radionuclide imaging (P2 = 0.026). Twenty-one of 26 (80.8%) treatment courses given with cyclophosphamide demonstrated tumor localization, compared with only 5 of 12 (41.7%) treatment courses without cyclophosphamide. In addition, patients whose 111In-labeled TIL imaged their tumor received significantly more TIL than did those that did not (P2 = 0.0052). Biopsies revealed a greater accumulation of 111In in cutaneous tumors than in normal skin biopsy specimens (0.0021 and 0.0004% injectate/gram of tissue, respectively; P2 = < 0.001). The median tumor-to-normal-skin ratio of simultaneous biopsies was 5.0. Finally, 10 of 26 (38.5%) patients who had tumor localization by scan had a clinical response, whereas no responses were noted in 12 patients whose tumors were not imaged (P2 = 0.022). CONCLUSIONS. Localization in tumor may be important in the mechanism of TIL antitumor activity because no clinical responses were seen in patients who did not have their tumors imaged with 111In-TIL. Cyclophosphamide administration before TIL and IL-2 therapy and the administration of large numbers of TIL appear to improve the frequency of TIL localization to tumor. 相似文献
993.
994.
The contraceptive efficacy of oral contraceptives (OCs) depends on their proper and continued use, particularly with lower estrogen preparations. However, few studies have examined why women miss pills or discontinue OCs, and those that do tend to be small and to focus on adolescents. To address the issues of poor OC compliance and early OC discontinuation, we analyzed OC use in a convenience sample of 6,676 women between the ages of 16 and 30 from Denmark, France, Italy, Portugal, and the United Kingdom. Logistic regression was used to examine the independent effect of each factor. Poor compliance was associated with a lack of established routine for pill-taking (relative risk [RR] = 3.3), failure to read and understand written materials that came with the OC package (RR = 2.2), not receiving adequate information or help about OCs from their health care provider (RR = 1.5), and occurrence of certain side effects, including hirsutism (RR = 2.1), nausea (RR = 1.4), bleeding irregularities (RR = 1.3), and breast tenderness (RR = 1.2). Women who were inconsistent OC users, missing one or more pills per cycle, were almost three times as likely to experience an unintended pregnancy while using OCs than were women who took their OCs consistently. Factors that predicted early discontinuation (women who wished to continue contraceptive protection but discontinued OC use) were primarily side effects, including nausea (RR = 2.1), bleeding (RR = 1.9), breast tenderness (RR = 1.8), mood changes (RR = 1.8), and weight gain (RR = 1.4).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
995.
We describe a fast computer algorithm for identifying consensus patterns in DNA sequences. The method requires no prior assumptions about the consensus pattern other than its length. In particular no previous knowledge of the frequency or spacing of consensus patterns is required. However, a priori information about the shape of the consensus pattern, or invariability of individual positions, or the overall conservation level, can be utilized to enhance the selectivity and sensitivity of search. As the number of all possible consensus words increases very rapidly with length, comprehensive searches have usually been restricted to a maximum of 10-12 nucleotides, even when large mainframes are used. Our algorithm enables searching for consensus patterns of this order on current mid-range and powerful microcomputers. Searches may be conducted on single, long sequences or a set of possibly aligned shorter sequences. We give examples of identified consensus patterns in both prokaryotic and eukaryotic DNA sequences, along with some typical program timings. 相似文献
996.
Accelerated Application Engineering (AAE) relies on many of the basic concepts employed in rapid prototyping and information engineering. By combining and tailoring these basics, the aim of AAE is to shorten the systems development life cycle. The features of the AAE approach are described in this article with consideration given to when and how it can be used for maximum effectiveness. 相似文献
997.
A Paavola J Yliruusi Y Kajimoto E Kalso T Wahlstr?m P Rosenberg 《Canadian Metallurgical Quarterly》1995,12(12):1997-2002
PURPOSE: Methods of delaying the action of local anesthetics are important, since short duration of action limits their use in the treatment of postoperative and chronic pain. The present study evaluated the use of low-viscosity gels in prolonging the release of lidocaine. METHODS: Release of lidocaine from 2% lidocaine.HCl containing methylcellulose (MC), hydroxypropylmethylcellulose (HPMC), sodiumcarboxymethyl cellulose (CMC), and poloxamer 407 (PO) gels was studied in phosphate buffer, pH 7.4, at 37 degrees C. Commercial metylcellulose gel (MCcom) served as control. The in vivo efficacy of the respective gel formulations were evaluated in rats. The gel was injected into the vicinity of the sciatic nerve and nociception and motor function were tested. RESULTS: The cumulative amount of lidocaine released during 8 hr was slowest from the PO gel, followed by the CMC, HPMC and MC gels. The antinociceptive effect was not prevented by the motor block and lasted longest with the PO gel. Good linear and rank order correlation was obtained between in vitro and in vivo results. The microscopic examination of the tissue samples revealed only mild or no irritation of the skeletal muscle tissue by the PO, HPMC, and CMC gels. CONCLUSIONS: Based on these results poloxamer gel proved to be the most promising carrier for lidocaine. 相似文献
998.
P Karila M Axelsson CE Franklin R Fritsche IL Gibbins GC Grigg S Nilsson S Holmgren 《Canadian Metallurgical Quarterly》1995,58(1-2):25-39
The two aortas of the crocodile are in open connection at two sites, the foramen of Panizzae immediately outside the ventricles, and the arterial anastomosis at the level of the gut. The present study was performed to elucidate the innervation of the cardiovascular structures of the crocodile, in part to provide a further basis for the assumption that the apertures of the foramen and the anastomosis may be altered, possibly leading to changes in the flow profiles of the central vessels. The presence of smooth muscle arranged at the circumference of the foramen and in the walls of the anastomosis was demonstrated. The cardiovascular structures were innervated by nerves containing co-existing tyrosine hydroxylase, NPY and somatostatin immunoreactivities, which also occurred in neurons of the sympathetic ganglia. CGRP and substance P immunoreactive material co-existed in cardiovascular nerves, and in the nodose ganglion. In addition, bombesin, VIP and galanin immunoreactive nerves were found. Effects of neuropeptides on blood flows and blood pressures were studied in vivo. Substance P increased all blood flows measured, NPY increased the flow through the arterial anastomosis while neurotensin caused an initial decrease in the flow through the arterial anastomosis. In conclusion, there is a rich innervation of the heart and major vessels of the estuarine crocodile, including the foramen of Panizza and the arterial anastomosis. These nerves possibly regulate the distribution of blood in the cardiovascular system, which is further suggested by the results of the injection of neuropeptides. 相似文献
999.
1000.
Discusses ways in which professional practice review (PR) may affect the consumer of mental health services. Cost containment and quality control are the major purposes of PR. PR appears to more effectively control utilization of services than cost per unit. PR may increase quality of service by establishing a better data base for evaluating treatment and outcome. Although PR may decrease costs and increase quality, it may also infringe on the privacy of the clients and narrow their freedom in choosing a provider. It is concluded that consumers need to be involved to make sure that PR addresses issues of importance to them, such as humaneness of treatment and control of poorly prepared providers. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献