全文获取类型
收费全文 | 1946篇 |
免费 | 2篇 |
专业分类
化学工业 | 9篇 |
能源动力 | 3篇 |
轻工业 | 3篇 |
无线电 | 2篇 |
一般工业技术 | 2篇 |
冶金工业 | 1925篇 |
自动化技术 | 4篇 |
出版年
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2013年 | 2篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2007年 | 1篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
1999年 | 53篇 |
1998年 | 617篇 |
1997年 | 312篇 |
1996年 | 196篇 |
1995年 | 137篇 |
1994年 | 123篇 |
1993年 | 127篇 |
1992年 | 24篇 |
1991年 | 25篇 |
1990年 | 15篇 |
1989年 | 21篇 |
1988年 | 21篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 20篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 28篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 42篇 |
1976年 | 99篇 |
1975年 | 5篇 |
1964年 | 1篇 |
排序方式: 共有1948条查询结果,搜索用时 15 毫秒
991.
992.
Regulation of cell growth by IL-2: role of STAT5 in protection from apoptosis but not in cell cycle progression 总被引:1,自引:0,他引:1
J Zamorano HY Wang R Wang Y Shi GD Longmore AD Keegan 《Canadian Metallurgical Quarterly》1998,160(7):3502-3512
Cytokines play an essential role in the regulation of lymphocyte survival and growth. We have analyzed the pathways activated by IE-2 that lead to protection from apoptosis and cell proliferation. IL-2 can act as a long-term growth factor in 32D cells expressing the wild-type human (hu)IL-2R beta. By contrast, cells expressing a truncated form of the huIL-2R beta, which is able to induce Bcl-2 and c-myc expression but not STAT5 activation, were not protected from apoptosis by IL-2; consequently, they could not be grown long term in the presence of IL-2. However, IL-2 promoted cell cycle progression in cells bearing the truncated huIL-2R beta with percentages of viable cells in the G0/G1, S, and G2/M phases similar to cells expressing the wild-type huIL-2R beta. Transplantation of a region from the erythropoietin receptor, which contains a docking site for STAT5 (Y343) to the truncated huIL-2R beta, restored the ability of IL-2 to signal both activation of STAT5 and protection from apoptosis. By contrast, transplantation of a region from the huIL-4R alpha containing STAT6 docking sites did not confer protection from apoptosis. These results indicate that the IL-2-induced cell cycle progression can be clearly distinguished from protection from apoptosis and that STAT5 participates in the regulation of apoptosis. 相似文献
993.
Z Popovi? M Miri? J Vasiljevi? D Sagi? M Boji? AD Popovi? 《Canadian Metallurgical Quarterly》1998,81(6):801-804
This clinical case report demonstrates the clinical effectiveness of a new form of soft tissue mobilization in the treatment of excessive connective tissue fibrosis (scar tissue) around an athlete's injured ankle. The scar tissue was causing the athlete to have pain with activity, pain on palpation of the ankle, decreased range of motion, and loss of function. Surgery and several months of conventional physical therapy failed to alleviate the athlete's symptoms. As a final resort, augmented soft tissue mobilization (ASTM) was administered. ASTM is an alternative nonsurgical treatment modality that is being researched at Performance Dynamics (Muncip, IN). ASTM is a process that uses ergonomically designed instruments that assist therapists in the rapid localization and effective treatment of areas exhibiting excessive soft tissue fibrosis. This is followed by a stretching and strengthening program. Upon the completion of 6 wk of ASTM therapy, the athlete had no pain and had regained full range of motion and function. This case report is an example of how a noninvasive augmented form of soft tissue mobilization (ASTM) demonstrated impressive clinical results in treating a condition caused by connective tissue fibrosis. 相似文献
994.
This paper describes a measure of explained variation (MEV) of survival times for a given regression model used in survival analysis. It quantifies the predictive power of a set of prognostic factors in the model, and therefore provides useful information for more precise prediction of patient prognosis, and for designing randomized clinical trials with the capability of determining treatment effects. The MEV defined in this article is asymptotically derived from the squared product-moment correlation; it can be interpreted as an adaptation of the multiple correlation coefficient for the normal linear model to the survival time regression model. Monte-Carlo simulations are performed to investigate the statistical behavior of the proposed MEV. The MEV is applied to estimate the predictive power of several sets of prognostic factors for gastric cancer in Japan using data from a large clinical trial. 相似文献
995.
DW Sanders AD Milne A Dobravec J MacDermid JA Johnson GJ King 《Canadian Metallurgical Quarterly》1997,22(6):1004-1010
Forty cadaveric flexor digitorum profundus tendons were repaired using the Tajima, Halsted, Silfverskiold, or Savage techniques. The tendons were cyclically loaded in sets of 4,000 cycles beginning at 25 N and increasing by 10-N increments until failure occurred. Gap formation was continuously monitored with an extensiometer. Only the Savage repair group consistently withstood 4,000 cycles of 25-N loading, with respect to 2-mm gap formation and repair rupture. Tendon repairs subjected to cyclic loading demonstrated gap formation and repair rupture at lower loads than with static testing. Of the methods of flexor tendon repair tested, only the Savage technique could withstand simulated early active motion. 相似文献
996.
997.
BACKGROUND: The eosinophil granulocyte is an inflammatory cell that plays an active part in diseases such as asthma and rhinitis. This study aimed to investigate oxidative metabolism by blood eosinophils taken from allergic rhinitis patients, asthmatics, and nonallergic controls before and during the birch-pollen season. METHODS: Twenty patients with allergy to birch pollen and seasonal symptoms of rhinitis, some of whom were also asthmatic, were followed before and during the birch-pollen season in Sweden. The cells were purified using a Percoll gradient and the MACS system. Eosinophil purity in all samples was > 95%. Oxidative metabolism was measured by a chemiluminescence (CL) assay, with luminol and lucigenin acting as enhancers, and PMA, serum-treated zymosan (STZ), interleukin (IL)-5, or RANTES as stimuli. RESULTS: The allergic subjects showed reduced luminol CL when activated before the season with PMA (P = 0.040) or STZ (P = 0.0055). This was not seen during pollen exposure. STZ-activated lucigenin CL was also reduced before the season (P = 0.0027). The reduction was most evident in the group with asymptomatic rhinitis. In terms of eosinophil stimulation, IL-5 and RANTES were equally effective in allergic and nonallergic subjects, both before and during the pollen season. CONCLUSIONS: Blood eosinophils from asymptomatic allergics may have a lower capacity to produce oxygen-free radicals than eosinophils from nonallergics. 相似文献
998.
J Groen G Van Dijk HG Niesters WI Van Der Meijden AD Osterhaus 《Canadian Metallurgical Quarterly》1998,36(3):845-847
The sensitivities and specificities of three immunoassays for the detection of herpes simplex virus type 2 (HSV-2)-specific immunoglobulin G antibodies in serum, including the one-strip rapid immunoblot assay (RIBA; Chiron Corporation) and two indirect enzyme immunosorbent assays (EIA; Gull Laboratories and Centocor), were compared by testing a panel of 1,250 serum samples from individuals attending an outpatient clinic for sexually transmitted diseases. A qualitative agreement among the three assays was observed with 1,080 serum samples (86.4%); 291 of the serum samples (23.3%) were positive, 789 samples (63.1%) were negative, and 170 serum samples (13.6%) gave a discordant result. Results were considered conclusive when a concordant result was obtained with two of three assays. The sensitivities and specificities of the RIBA, the Gull EIA, and the Centocor EIA proved to be 99.2, 99.7, and 89.9% and 97.1, 96.7, and 99.3%, respectively. These results indicate that the Chiron RIBA and the Gull EIA are especially useful and reliable for the detection of HSV-2-specific antibodies in serum. 相似文献
999.
M Zecevic AD Catling ST Eblen L Renzi JC Hittle TJ Yen GJ Gorbsky MJ Weber 《Canadian Metallurgical Quarterly》1998,142(6):1547-1558
To investigate possible involvement of the mitogen-activated protein (MAP) kinases ERK1 and ERK2 (extracellular signal-regulated kinases) in somatic cell mitosis, we have used indirect immunofluorescence with a highly specific phospho-MAP kinase antibody and found that a portion of the active MAP kinase is localized at kinetochores, asters, and the midbody during mitosis. Although the aster labeling was constant from the time of nuclear envelope breakdown, the kinetochore labeling first appeared at early prometaphase, started to fade during chromosome congression, and then disappeared at midanaphase. At telophase, active MAP kinase localized at the midbody. Based on colocalization and the presence of a MAP kinase consensus phosphorylation site, we identified the kinetochore motor protein CENP-E as a candidate mitotic substrate for MAP kinase. CENP-E was phosphorylated in vitro by MAP kinase on sites that are known to regulate its interactions with microtubules and was found to associate in vivo preferentially with the active MAP kinase during mitosis. Therefore, the presence of active MAP kinase at specific mitotic structures and its interaction with CENP-E suggest that MAP kinase could play a role in mitosis at least in part by altering the ability of CENP-E to mediate interactions between chromosomes and microtubules. 相似文献
1000.
We studied 2 groups of patients with (n = 14) and without (n = 42) minor coronary dissections following cutting balloon angioplasty. Patients with a minor dissection had a longer length of lesion, higher percentage of stenosis, and greater acute gain after angioplasty; at 6-month follow-up both groups had a similar net gain and restenosis rate, suggesting that minor dissection after cutting balloon angioplasty has no influence on restenosis. 相似文献